Obesity
Overview
Obesity is a medical condition in which excess body fat has accumulated to the extent that it may have an adverse effect on health, leading to reduced life expectancy
Life expectancy
Life expectancy is the expected number of years of life remaining at a given age. It is denoted by ex, which means the average number of subsequent years of life for someone now aged x, according to a particular mortality experience...

 and/or increased health problems. Body mass index
Body mass index
The body mass index , or Quetelet index, is a heuristic proxy for human body fat based on an individual's weight and height. BMI does not actually measure the percentage of body fat. It was invented between 1830 and 1850 by the Belgian polymath Adolphe Quetelet during the course of developing...

 (BMI), a measurement which compares weight and height, defines people as overweight
Overweight
Overweight is generally defined as having more body fat than is optimally healthy. Being overweight is a common condition, especially where food supplies are plentiful and lifestyles are sedentary...

 (pre-obese) if their BMI is between 25 and 30 kg/m2, and obese when it is greater than 30 kg/m2.

Obesity increases the likelihood of various diseases
Obesity associated morbidity
Whether obesity should be considered a disease on its own, it is also an important risk factor for many chronic physical and mental illnesses.-Ischemic heart disease:Obesity is associated with cardiovascular diseases including angina and myocardial infarction...

, particularly heart disease, type 2 diabetes
Diabetes mellitus type 2
Diabetes mellitus type 2formerly non-insulin-dependent diabetes mellitus or adult-onset diabetesis a metabolic disorder that is characterized by high blood glucose in the context of insulin resistance and relative insulin deficiency. Diabetes is often initially managed by increasing exercise and...

, obstructive sleep apnea
Obstructive sleep apnea
Obstructive sleep apnea or obstructive sleep apnea syndrome is the most common type of sleep apnea and is caused by obstruction of the upper airway. It is characterized by repetitive pauses in breathing during sleep, despite the effort to breathe, and is usually associated with a reduction in...

, certain types of cancer
Cancer
Cancer , known medically as a malignant neoplasm, is a large group of different diseases, all involving unregulated cell growth. In cancer, cells divide and grow uncontrollably, forming malignant tumors, and invade nearby parts of the body. The cancer may also spread to more distant parts of the...

, and osteoarthritis
Osteoarthritis
Osteoarthritis also known as degenerative arthritis or degenerative joint disease, is a group of mechanical abnormalities involving degradation of joints, including articular cartilage and subchondral bone. Symptoms may include joint pain, tenderness, stiffness, locking, and sometimes an effusion...

.
Encyclopedia
Obesity is a medical condition in which excess body fat has accumulated to the extent that it may have an adverse effect on health, leading to reduced life expectancy
Life expectancy
Life expectancy is the expected number of years of life remaining at a given age. It is denoted by ex, which means the average number of subsequent years of life for someone now aged x, according to a particular mortality experience...

 and/or increased health problems. Body mass index
Body mass index
The body mass index , or Quetelet index, is a heuristic proxy for human body fat based on an individual's weight and height. BMI does not actually measure the percentage of body fat. It was invented between 1830 and 1850 by the Belgian polymath Adolphe Quetelet during the course of developing...

 (BMI), a measurement which compares weight and height, defines people as overweight
Overweight
Overweight is generally defined as having more body fat than is optimally healthy. Being overweight is a common condition, especially where food supplies are plentiful and lifestyles are sedentary...

 (pre-obese) if their BMI is between 25 and 30 kg/m2, and obese when it is greater than 30 kg/m2.

Obesity increases the likelihood of various diseases
Obesity associated morbidity
Whether obesity should be considered a disease on its own, it is also an important risk factor for many chronic physical and mental illnesses.-Ischemic heart disease:Obesity is associated with cardiovascular diseases including angina and myocardial infarction...

, particularly heart disease, type 2 diabetes
Diabetes mellitus type 2
Diabetes mellitus type 2formerly non-insulin-dependent diabetes mellitus or adult-onset diabetesis a metabolic disorder that is characterized by high blood glucose in the context of insulin resistance and relative insulin deficiency. Diabetes is often initially managed by increasing exercise and...

, obstructive sleep apnea
Obstructive sleep apnea
Obstructive sleep apnea or obstructive sleep apnea syndrome is the most common type of sleep apnea and is caused by obstruction of the upper airway. It is characterized by repetitive pauses in breathing during sleep, despite the effort to breathe, and is usually associated with a reduction in...

, certain types of cancer
Cancer
Cancer , known medically as a malignant neoplasm, is a large group of different diseases, all involving unregulated cell growth. In cancer, cells divide and grow uncontrollably, forming malignant tumors, and invade nearby parts of the body. The cancer may also spread to more distant parts of the...

, and osteoarthritis
Osteoarthritis
Osteoarthritis also known as degenerative arthritis or degenerative joint disease, is a group of mechanical abnormalities involving degradation of joints, including articular cartilage and subchondral bone. Symptoms may include joint pain, tenderness, stiffness, locking, and sometimes an effusion...

. Obesity is most commonly caused by a combination of excessive food energy
Food energy
Food energy is the amount of energy obtained from food that is available through cellular respiration.Food energy is expressed in food calories or kilojoules...

 intake, lack of physical activity, and genetic susceptibility, although a few cases are caused primarily by gene
Gene
A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...

s, endocrine disorders, medication
Medication
A pharmaceutical drug, also referred to as medicine, medication or medicament, can be loosely defined as any chemical substance intended for use in the medical diagnosis, cure, treatment, or prevention of disease.- Classification :...

s or psychiatric illness. Evidence to support the view that some obese people eat little yet gain weight due to a slow metabolism is limited; on average obese people have a greater energy expenditure than their thin counterparts due to the energy required to maintain an increased body mass.

Dieting
Dieting
Dieting is the practice of eating food in a regulated fashion to achieve or maintain a controlled weight. In most cases dieting is used in combination with physical exercise to lose weight in those who are overweight or obese. Some athletes, however, follow a diet to gain weight...

 and physical exercise
Physical exercise
Physical exercise is any bodily activity that enhances or maintains physical fitness and overall health and wellness. It is performed for various reasons including strengthening muscles and the cardiovascular system, honing athletic skills, weight loss or maintenance, as well as for the purpose of...

 are the mainstays of treatment for obesity. Moreover, it is important to improve diet quality by reducing the consumption of energy-dense foods such as those high in fat and sugars, and by increasing the intake of dietary fiber
Dietary fiber
Dietary fiber, dietary fibre, or sometimes roughage is the indigestible portion of plant foods having two main components:* soluble fiber that is readily fermented in the colon into gases and physiologically active byproducts, and* insoluble fiber that is metabolically inert, absorbing water as it...

. To supplement this, or in case of failure, anti-obesity drug
Anti-obesity drug
Anti-obesity medication or weight loss drugs are all pharmacological agents that reduce or control weight. These drugs alter one of the fundamental processes of the human body, weight regulation, by either altering appetite, metabolism, or absorption of calories. It is common for them to be tried...

s may be taken to reduce appetite or inhibit fat absorption. In severe cases, surgery
Bariatric surgery
Bariatric surgery includes a variety of procedures performed on people who are obese. Weight loss is achieved by reducing the size of the stomach with an implanted medical device or through removal of a portion of the stomach or by resecting and re-routing the small intestines...

 is performed or an intragastric balloon is placed to reduce stomach volume and/or bowel length, leading to earlier satiation and reduced ability to absorb nutrients from food.

Obesity is a leading preventable cause of death
Preventable causes of death
The World Health Organization has traditionally classified death according to the primary type of disease or injury. However, causes of death may also be classified in terms of preventable risk factors—such as smoking, unhealthy diet, and sexual behavior—which contribute to a number of different...

 worldwide, with increasing prevalence
Prevalence
In epidemiology, the prevalence of a health-related state in a statistical population is defined as the total number of cases of the risk factor in the population at a given time, or the total number of cases in the population, divided by the number of individuals in the population...

 in adults and children
Childhood obesity
Childhood obesity is a condition where excess body fat negatively affects a child's health or wellbeing. As methods to determine body fat directly are difficult, the diagnosis of obesity is often based on BMI. Due to the rising prevalence of obesity in children and its many adverse health effects...

, and authorities view it as one of the most serious public health
Public health
Public health is "the science and art of preventing disease, prolonging life and promoting health through the organized efforts and informed choices of society, organizations, public and private, communities and individuals" . It is concerned with threats to health based on population health...

 problems of the 21st century. Obesity is stigmatized
Weight Stigma
Weight stigma, also known as weightism, weight bias, and weight-based discrimination, is discrimination or stereotyping based on one's weight, especially very large or thin people...

 in much of the modern world (particularly in the Western world
Western world
The Western world, also known as the West and the Occident , is a term referring to the countries of Western Europe , the countries of the Americas, as well all countries of Northern and Central Europe, Australia and New Zealand...

), though it was widely perceived as a symbol of wealth and fertility at other times in history, and still is in some parts of the world.

Classification

Obesity is a medical condition in which excess body fat has accumulated to the extent that it may have an adverse effect on health. It is defined by body mass index (BMI)
Body mass index
The body mass index , or Quetelet index, is a heuristic proxy for human body fat based on an individual's weight and height. BMI does not actually measure the percentage of body fat. It was invented between 1830 and 1850 by the Belgian polymath Adolphe Quetelet during the course of developing...

 and further evaluated in terms of fat distribution via the waist–hip ratio and total cardiovascular risk factors. BMI is closely related to both percentage body fat
Body fat percentage
A person's body mass percentage is the total weight of the person's fat divided by the person's weight and consists of essential body fat and storage body fat. Essential body fat is necessary to maintain life and reproductive functions. The percentage of essential body fat for women is greater than...

 and total body fat.

In children, a healthy weight varies with age and sex. Obesity in children and adolescents is defined not as an absolute number, but in relation to a historical normal group, such that obesity is a BMI greater than the 95th percentile
Percentile
In statistics, a percentile is the value of a variable below which a certain percent of observations fall. For example, the 20th percentile is the value below which 20 percent of the observations may be found...

. The reference data on which these percentiles were based date from 1963 to 1994, and thus have not been affected by the recent increases in weight.
BMI Classification
< 18.5 underweight
18.5–24.9 normal weight
25.0–29.9 overweight
30.0–34.9 class I obesity
35.0–39.9 class II obesity
≥ 40.0   class III obesity  


BMI is calculated by dividing the subject's mass by the square of his or her height, typically expressed either in metric
Metric system
The metric system is an international decimalised system of measurement. France was first to adopt a metric system, in 1799, and a metric system is now the official system of measurement, used in almost every country in the world...

 or US "customary" units:
Metric:

US customary and imperial:


where is the subject's weight in pounds
Pound (mass)
The pound or pound-mass is a unit of mass used in the Imperial, United States customary and other systems of measurement...

 and is the subject's height in inches.

The most commonly used definitions, established by the World Health Organization
World Health Organization
The World Health Organization is a specialized agency of the United Nations that acts as a coordinating authority on international public health. Established on 7 April 1948, with headquarters in Geneva, Switzerland, the agency inherited the mandate and resources of its predecessor, the Health...

 (WHO) in 1997 and published in 2000, provide the values listed in the table at right.

Some modifications to the WHO definitions have been made by particular bodies. The surgical literature breaks down "class III" obesity into further categories whose exact values are still disputed.
  • Any BMI ≥ 35 or 40 is severe obesity
  • A BMI of ≥ 35 or 40–44.9 or 49.9 is morbid obesity
  • A BMI of ≥ 45 or 50 is super obesity


As Asian populations develop negative health consequences at a lower BMI than Caucasians, some nations have redefined obesity; the Japanese have defined obesity as any BMI greater than 25 while China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...

 uses a BMI of greater than 28.

Effects on health

Excessive body weight is associated with various diseases, particularly cardiovascular diseases, diabetes mellitus type 2
Diabetes mellitus type 2
Diabetes mellitus type 2formerly non-insulin-dependent diabetes mellitus or adult-onset diabetesis a metabolic disorder that is characterized by high blood glucose in the context of insulin resistance and relative insulin deficiency. Diabetes is often initially managed by increasing exercise and...

, obstructive sleep apnea
Obstructive sleep apnea
Obstructive sleep apnea or obstructive sleep apnea syndrome is the most common type of sleep apnea and is caused by obstruction of the upper airway. It is characterized by repetitive pauses in breathing during sleep, despite the effort to breathe, and is usually associated with a reduction in...

, certain types of cancer
Cancer
Cancer , known medically as a malignant neoplasm, is a large group of different diseases, all involving unregulated cell growth. In cancer, cells divide and grow uncontrollably, forming malignant tumors, and invade nearby parts of the body. The cancer may also spread to more distant parts of the...

, and osteoarthritis
Osteoarthritis
Osteoarthritis also known as degenerative arthritis or degenerative joint disease, is a group of mechanical abnormalities involving degradation of joints, including articular cartilage and subchondral bone. Symptoms may include joint pain, tenderness, stiffness, locking, and sometimes an effusion...

. As a result, obesity has been found to reduce life expectancy
Life expectancy
Life expectancy is the expected number of years of life remaining at a given age. It is denoted by ex, which means the average number of subsequent years of life for someone now aged x, according to a particular mortality experience...

.

Mortality

Obesity is one of the leading preventable causes of death
Preventable causes of death
The World Health Organization has traditionally classified death according to the primary type of disease or injury. However, causes of death may also be classified in terms of preventable risk factors—such as smoking, unhealthy diet, and sexual behavior—which contribute to a number of different...

 worldwide. Large-scale American and European studies have found that mortality risk is lowest at a BMI of 20–25 kg/m2 in non-smokers and at 24–27 kg/m2 in current smokers, with risk increasing along with changes in either direction. A BMI above 32 has been associated with a doubled mortality rate
Mortality rate
Mortality rate is a measure of the number of deaths in a population, scaled to the size of that population, per unit time...

 among women over a 16-year period. In the United States obesity is estimated to cause an excess 111,909 to 365,000 deaths per year, while 1 million (7.7%) of deaths in the European Union are attributed to excess weight. On average, obesity reduces life expectancy by six to seven years: a BMI of 30–35 reduces life expectancy by two to four years, while severe obesity (BMI > 40) reduces life expectancy by 10 years.

Morbidity

Obesity increases the risk of many physical and mental conditions. These comorbidities are most commonly shown in metabolic syndrome
Metabolic syndrome
Metabolic syndrome is a combination of medical disorders that, when occurring together, increase the risk of developing cardiovascular disease and diabetes. It affects one in five people in the United States and prevalence increases with age...

, a combination of medical disorders which includes: diabetes mellitus type 2
Diabetes mellitus type 2
Diabetes mellitus type 2formerly non-insulin-dependent diabetes mellitus or adult-onset diabetesis a metabolic disorder that is characterized by high blood glucose in the context of insulin resistance and relative insulin deficiency. Diabetes is often initially managed by increasing exercise and...

, high blood pressure
Hypertension
Hypertension or high blood pressure is a cardiac chronic medical condition in which the systemic arterial blood pressure is elevated. What that means is that the heart is having to work harder than it should to pump the blood around the body. Blood pressure involves two measurements, systolic and...

, high blood cholesterol
Hypercholesterolemia
Hypercholesterolemia is the presence of high levels of cholesterol in the blood. It is not a disease but a metabolic derangement that can be caused by many diseases, notably cardiovascular disease...

, and high triglyceride levels
Hypertriglyceridemia
In medicine, hypertriglyceridemia denotes high blood levels of triglycerides, the most abundant fatty molecule in most organisms. It has been associated with atherosclerosis, even in the absence of hypercholesterolemia . It can also lead to pancreatitis in excessive concentrations In medicine,...

.

Complications are either directly caused by obesity or indirectly related through mechanisms sharing a common cause such as a poor diet or a sedentary lifestyle
Sedentary lifestyle
Sedentary lifestyle is a medical term used to denote a type of lifestyle with no or irregular physical activity. A person who lives a sedentary lifestyle may colloquially be known as a couch potato. It is commonly found in both the developed and developing world...

. The strength of the link between obesity and specific conditions varies. One of the strongest is the link with type 2 diabetes. Excess body fat underlies 64% of cases of diabetes in men and 77% of cases in women.

Health consequences fall into two broad categories: those attributable to the effects of increased fat mass (such as osteoarthritis
Osteoarthritis
Osteoarthritis also known as degenerative arthritis or degenerative joint disease, is a group of mechanical abnormalities involving degradation of joints, including articular cartilage and subchondral bone. Symptoms may include joint pain, tenderness, stiffness, locking, and sometimes an effusion...

, obstructive sleep apnea
Obstructive sleep apnea
Obstructive sleep apnea or obstructive sleep apnea syndrome is the most common type of sleep apnea and is caused by obstruction of the upper airway. It is characterized by repetitive pauses in breathing during sleep, despite the effort to breathe, and is usually associated with a reduction in...

, social stigmatization) and those due to the increased number of fat cells (diabetes
Diabetes mellitus
Diabetes mellitus, often simply referred to as diabetes, is a group of metabolic diseases in which a person has high blood sugar, either because the body does not produce enough insulin, or because cells do not respond to the insulin that is produced...

, cancer
Cancer
Cancer , known medically as a malignant neoplasm, is a large group of different diseases, all involving unregulated cell growth. In cancer, cells divide and grow uncontrollably, forming malignant tumors, and invade nearby parts of the body. The cancer may also spread to more distant parts of the...

, cardiovascular disease
Cardiovascular disease
Heart disease or cardiovascular disease are the class of diseases that involve the heart or blood vessels . While the term technically refers to any disease that affects the cardiovascular system , it is usually used to refer to those related to atherosclerosis...

, non-alcoholic fatty liver disease
Non-alcoholic fatty liver disease
Non-alcoholic fatty liver disease is one cause of a fatty liver, occurring when fat is deposited in the liver not due to excessive alcohol use. It is related to insulin resistance and the metabolic syndrome and may respond to treatments originally developed for other insulin-resistant states...

). Increases in body fat alter the body's response to insulin, potentially leading to insulin resistance
Insulin resistance
Insulin resistance is a physiological condition where the natural hormone insulin becomes less effective at lowering blood sugars. The resulting increase in blood glucose may raise levels outside the normal range and cause adverse health effects, depending on dietary conditions. Certain cell types...

. Increased fat also creates a proinflammatory state
Inflammation
Inflammation is part of the complex biological response of vascular tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. Inflammation is a protective attempt by the organism to remove the injurious stimuli and to initiate the healing process...

, and a prothrombotic
Thrombosis
Thrombosis is the formation of a blood clot inside a blood vessel, obstructing the flow of blood through the circulatory system. When a blood vessel is injured, the body uses platelets and fibrin to form a blood clot to prevent blood loss...

 state.
Medical field Condition Medical field Condition
Cardiology
Cardiology
Cardiology is a medical specialty dealing with disorders of the heart . The field includes diagnosis and treatment of congenital heart defects, coronary artery disease, heart failure, valvular heart disease and electrophysiology...

  • ischemic heart disease: angina and myocardial infarction
    Myocardial infarction
    Myocardial infarction or acute myocardial infarction , commonly known as a heart attack, results from the interruption of blood supply to a part of the heart, causing heart cells to die...

  • congestive heart failure
    Congestive heart failure
    Heart failure often called congestive heart failure is generally defined as the inability of the heart to supply sufficient blood flow to meet the needs of the body. Heart failure can cause a number of symptoms including shortness of breath, leg swelling, and exercise intolerance. The condition...

  • high blood pressure
  • abnormal cholesterol levels
    Dyslipidemia
    Dyslipidemia or dyslipidaemia is an abnormal amount of lipids in the blood. In developed countries, most dyslipidemias are hyperlipidemias; that is, an elevation of lipids in the blood, often due to diet and lifestyle. The prolonged elevation of insulin levels can lead to dyslipidemia...

  • deep vein thrombosis
    Deep vein thrombosis
    Deep vein thrombosis is the formation of a blood clot in a deep vein. Deep vein thrombosis commonly affects the leg veins or the deep veins of the pelvis. Occasionally the veins of the arm are affected...

     and pulmonary embolism
    Pulmonary embolism
    Pulmonary embolism is a blockage of the main artery of the lung or one of its branches by a substance that has travelled from elsewhere in the body through the bloodstream . Usually this is due to embolism of a thrombus from the deep veins in the legs, a process termed venous thromboembolism...

Dermatology
Dermatology
Dermatology is the branch of medicine dealing with the skin and its diseases, a unique specialty with both medical and surgical aspects. A dermatologist takes care of diseases, in the widest sense, and some cosmetic problems of the skin, scalp, hair, and nails....

  • stretch marks
  • acanthosis nigricans
    Acanthosis nigricans
    Acanthosis nigricans is a brown to black, poorly defined, velvety hyperpigmentation of the skin. It is usually found in body folds, such as the posterior and lateral folds of the neck, the axilla, groin, umbilicus, forehead, and other areas.-Causes:...

  • lymphedema
    Lymphedema
    Lymphedema , also known as lymphatic obstruction, is a condition of localized fluid retention and tissue swelling caused by a compromised lymphatic system....

  • cellulitis
    Cellulitis
    Cellulitis is a diffuse inflammation of connective tissue with severe inflammation of dermal and subcutaneous layers of the skin. Cellulitis can be caused by normal skin flora or by exogenous bacteria, and often occurs where the skin has previously been broken: cracks in the skin, cuts, blisters,...

  • hirsutism
    Hirsutism
    Hirsutism or frazonism is the excessive hairiness on women in those parts of the body where terminal hair does not normally occur or is minimal - for example, a beard or chest hair. It refers to a male pattern of body hair and it is therefore primarily of cosmetic and psychological concern...

  • intertrigo
    Intertrigo
    An intertrigo is an inflammation of the body folds .An intertrigo sometimes refers to a bacterial, fungal, or viral infection that has developed at the site of broken skin due to such inflammation...

  • Endocrinology
    Endocrinology
    Endocrinology is a branch of biology and medicine dealing with the endocrine system, its diseases, and its specific secretions called hormones, the integration of developmental events such as proliferation, growth, and differentiation and the coordination of...

     and Reproductive medicine
    Reproductive medicine
    Reproductive medicine is a branch of medicine that deals with prevention, diagnosis and management of reproductive problems; goals include improving or maintaining reproductive health and allowing people to have children at a time of their choosing...

  • diabetes mellitus
    Diabetes mellitus
    Diabetes mellitus, often simply referred to as diabetes, is a group of metabolic diseases in which a person has high blood sugar, either because the body does not produce enough insulin, or because cells do not respond to the insulin that is produced...

  • polycystic ovarian syndrome
  • menstrual
    Menstruation
    Menstruation is the shedding of the uterine lining . It occurs on a regular basis in sexually reproductive-age females of certain mammal species. This article focuses on human menstruation.-Overview:...

     disorders
  • infertility
    Infertility
    Infertility primarily refers to the biological inability of a person to contribute to conception. Infertility may also refer to the state of a woman who is unable to carry a pregnancy to full term...

  • complications during pregnancy
    Maternal obesity
    Maternal obesity refers to obesity of a woman during pregnancy. Parental obesity refers to obesity of either parent during pregnancy....

  • birth defects
  • intrauterine fetal death
    Stillbirth
    A stillbirth occurs when a fetus has died in the uterus. The Australian definition specifies that fetal death is termed a stillbirth after 20 weeks gestation or the fetus weighs more than . Once the fetus has died the mother still has contractions and remains undelivered. The term is often used in...

  • Gastrointestinal
  • gastroesophageal reflux disease
    Gastroesophageal reflux disease
    Gastroesophageal reflux disease , gastro-oesophageal reflux disease , gastric reflux disease, or acid reflux disease is chronic symptoms or mucosal damage caused by stomach acid coming up from the stomach into the esophagus...

  • fatty liver disease
    Non-alcoholic fatty liver disease
    Non-alcoholic fatty liver disease is one cause of a fatty liver, occurring when fat is deposited in the liver not due to excessive alcohol use. It is related to insulin resistance and the metabolic syndrome and may respond to treatments originally developed for other insulin-resistant states...

  • cholelithiasis (gallstones)
  • Neurology
    Neurology
    Neurology is a medical specialty dealing with disorders of the nervous system. Specifically, it deals with the diagnosis and treatment of all categories of disease involving the central, peripheral, and autonomic nervous systems, including their coverings, blood vessels, and all effector tissue,...

  • stroke
    Stroke
    A stroke, previously known medically as a cerebrovascular accident , is the rapidly developing loss of brain function due to disturbance in the blood supply to the brain. This can be due to ischemia caused by blockage , or a hemorrhage...

  • meralgia paresthetica
  • migraines
  • carpal tunnel syndrome
    Carpal tunnel syndrome
    Carpal Tunnel Syndrome is an entrapment idiopathic median neuropathy, causing paresthesia, pain, and other symptoms in the distribution of the median nerve due to its compression at the wrist in the carpal tunnel. The pathophysiology is not completely understood but can be considered compression...

  • dementia
    Dementia
    Dementia is a serious loss of cognitive ability in a previously unimpaired person, beyond what might be expected from normal aging...

  • idiopathic intracranial hypertension
    Idiopathic intracranial hypertension
    Idiopathic intracranial hypertension , sometimes called by the older names benign intracranial hypertension or pseudotumor cerebri , is a neurological disorder that is characterized by increased intracranial pressure in the absence of a tumor or other diseases...

  • multiple sclerosis
    Multiple sclerosis
    Multiple sclerosis is an inflammatory disease in which the fatty myelin sheaths around the axons of the brain and spinal cord are damaged, leading to demyelination and scarring as well as a broad spectrum of signs and symptoms...

  • Oncology
    Oncology
    Oncology is a branch of medicine that deals with cancer...

  • breast
    Breast cancer
    Breast cancer is cancer originating from breast tissue, most commonly from the inner lining of milk ducts or the lobules that supply the ducts with milk. Cancers originating from ducts are known as ductal carcinomas; those originating from lobules are known as lobular carcinomas...

    , ovarian
    Ovarian cancer
    Ovarian cancer is a cancerous growth arising from the ovary. Symptoms are frequently very subtle early on and may include: bloating, pelvic pain, difficulty eating and frequent urination, and are easily confused with other illnesses....

  • esophageal
    Esophageal cancer
    Esophageal cancer is malignancy of the esophagus. There are various subtypes, primarily squamous cell cancer and adenocarcinoma . Squamous cell cancer arises from the cells that line the upper part of the esophagus...

    , colorectal
    Colorectal cancer
    Colorectal cancer, commonly known as bowel cancer, is a cancer caused by uncontrolled cell growth , in the colon, rectum, or vermiform appendix. Colorectal cancer is clinically distinct from anal cancer, which affects the anus....

  • liver
    Hepatocellular carcinoma
    Hepatocellular carcinoma is the most common type of liver cancer. Most cases of HCC are secondary to either a viral hepatitide infection or cirrhosis .Compared to other cancers, HCC is quite a rare tumor in the United States...

    , pancreatic
    Pancreatic cancer
    Pancreatic cancer refers to a malignant neoplasm of the pancreas. The most common type of pancreatic cancer, accounting for 95% of these tumors is adenocarcinoma, which arises within the exocrine component of the pancreas. A minority arises from the islet cells and is classified as a...

  • gallbladder
    Gallbladder cancer
    Gallbladder cancer is a relatively uncommon cancer. It has peculiar geographical distribution being common in central and South America, central and eastern Europe, Japan and northern India; it is also common in certain ethnic groups e.g. Native American Indians and Hispanics. If it is diagnosed...

    , stomach
    Stomach cancer
    Gastric cancer, commonly referred to as stomach cancer, can develop in any part of the stomach and may spread throughout the stomach and to other organs; particularly the esophagus, lungs, lymph nodes, and the liver...

  • endometrial
    Endometrial cancer
    Endometrial cancer refers to several types of malignancies that arise from the endometrium, or lining, of the uterus. Endometrial cancers are the most common gynecologic cancers in the United States, with over 35,000 women diagnosed each year. The incidence is on a slow rise secondary to the...

    , cervical
    Cervical cancer
    Cervical cancer is malignant neoplasm of the cervix uteri or cervical area. One of the most common symptoms is abnormal vaginal bleeding, but in some cases there may be no obvious symptoms until the cancer is in its advanced stages...

  • prostate
    Prostate cancer
    Prostate cancer is a form of cancer that develops in the prostate, a gland in the male reproductive system. Most prostate cancers are slow growing; however, there are cases of aggressive prostate cancers. The cancer cells may metastasize from the prostate to other parts of the body, particularly...

    , kidney
    Renal cell carcinoma
    Renal cell carcinoma is a kidney cancer that originates in the lining of the proximal convoluted tubule, the very small tubes in the kidney that filter the blood and remove waste products. RCC is the most common type of kidney cancer in adults, responsible for approximately 80% of cases...

  • non-Hodgkin's lymphoma, multiple myeloma
    Multiple myeloma
    Multiple myeloma , also known as plasma cell myeloma or Kahler's disease , is a cancer of plasma cells, a type of white blood cell normally responsible for the production of antibodies...

  • Psychiatry
    Psychiatry
    Psychiatry is the medical specialty devoted to the study and treatment of mental disorders. These mental disorders include various affective, behavioural, cognitive and perceptual abnormalities...

  • depression in women
  • social stigmatization
  • Respirology
  • obstructive sleep apnea
    Sleep apnea
    Sleep apnea is a sleep disorder characterized by abnormal pauses in breathing or instances of abnormally low breathing, during sleep. Each pause in breathing, called an apnea, can last from a few seconds to minutes, and may occur 5 to 30 times or more an hour. Similarly, each abnormally low...

  • obesity hypoventilation syndrome
  • asthma
    Asthma
    Asthma is the common chronic inflammatory disease of the airways characterized by variable and recurring symptoms, reversible airflow obstruction, and bronchospasm. Symptoms include wheezing, coughing, chest tightness, and shortness of breath...

  • increased complications during general anaesthesia
    General anaesthesia
    General anaesthesia is a state of unconsciousness and loss of protective reflexes resulting from the administration of one or more general anaesthetic agents...

  • Rheumatology
    Rheumatology
    Rheumatology is a sub-specialty in internal medicine and pediatrics, devoted to diagnosis and therapy of rheumatic diseases. Clinicians who specialize in rheumatology are called rheumatologists...

     and Orthopedics
    Orthopedics
    Orthopedics is the study of the musculoskeletal system. The Greek word 'ortho' means straight or correct and 'pedics' comes from the Greek 'pais' meaning children. For many centuries, orthopedists have been involved in the treatment of crippled children...

  • gout
    Gout
    Gout is a medical condition usually characterized by recurrent attacks of acute inflammatory arthritis—a red, tender, hot, swollen joint. The metatarsal-phalangeal joint at the base of the big toe is the most commonly affected . However, it may also present as tophi, kidney stones, or urate...

  • poor mobility
  • osteoarthritis
    Osteoarthritis
    Osteoarthritis also known as degenerative arthritis or degenerative joint disease, is a group of mechanical abnormalities involving degradation of joints, including articular cartilage and subchondral bone. Symptoms may include joint pain, tenderness, stiffness, locking, and sometimes an effusion...

  • low back pain
    Low back pain
    Low back pain or lumbago is a common musculoskeletal disorder affecting 80% of people at some point in their lives. In the United States it is the most common cause of job-related disability, a leading contributor to missed work, and the second most common neurological ailment — only headache is...

  • Urology
    Urology
    Urology is the medical and surgical specialty that focuses on the urinary tracts of males and females, and on the reproductive system of males. Medical professionals specializing in the field of urology are called urologists and are trained to diagnose, treat, and manage patients with urological...

     and Nephrology
    Nephrology
    Nephrology is a branch of internal medicine and pediatrics dealing with the study of the function and diseases of the kidney.-Scope of the specialty:...

  • erectile dysfunction
    Erectile dysfunction
    Erectile dysfunction is sexual dysfunction characterized by the inability to develop or maintain an erection of the penis during sexual performance....

  • urinary incontinence
    Urinary incontinence
    Urinary incontinence is any involuntary leakage of urine. It is a common and distressing problem, which may have a profound impact on quality of life. Urinary incontinence almost always results from an underlying treatable medical condition but is under-reported to medical practitioners...

  • chronic renal failure
    Chronic renal failure
    Chronic kidney disease , also known as chronic renal disease, is a progressive loss in renal function over a period of months or years. The symptoms of worsening kidney function are unspecific, and might include feeling generally unwell and experiencing a reduced appetite...

  • hypogonadism
    Hypogonadism
    Hypogonadism is a medical term for decreased functional activity of the gonads. Low testosterone is caused by a decline or deficiency in gonadal production of testosterone in males...


  • Survival paradox

    Although the negative health consequences of obesity in the general population are well supported by the available evidence, health outcomes in certain subgroups seem to be improved at an increased BMI, a phenomenon known as the obesity survival paradox. The paradox was first described in 1999 in overweight and obese people undergoing hemodialysis, and has subsequently been found in those with heart failure and peripheral artery disease (PAD).

    In people with heart failure, those with a BMI between 30.0 and 34.9 had lower mortality than those with a normal weight. This has been attributed to the fact that people often lose weight as they become progressively more ill. Similar findings have been made in other types of heart disease. People with class I obesity and heart disease do not have greater rates of further heart problems than people of normal weight who also have heart disease. In people with greater degrees of obesity, however, risk of further events is increased. Even after cardiac bypass surgery
    Coronary artery bypass surgery
    Coronary artery bypass surgery, also coronary artery bypass graft surgery, and colloquially heart bypass or bypass surgery is a surgical procedure performed to relieve angina and reduce the risk of death from coronary artery disease...

    , no increase in mortality is seen in the overweight and obese. One study found that the improved survival could be explained by the more aggressive treatment obese people receive after a cardiac event. Another found that if one takes into account chronic obstructive pulmonary disease
    Chronic obstructive pulmonary disease
    Chronic obstructive pulmonary disease , also known as chronic obstructive lung disease , chronic obstructive airway disease , chronic airflow limitation and chronic obstructive respiratory disease , is the co-occurrence of chronic bronchitis and emphysema, a pair of commonly co-existing diseases...

     (COPD) in those with PAD the benefit of obesity no longer exists.

    Causes

    At an individual level, a combination of excessive food energy
    Food energy
    Food energy is the amount of energy obtained from food that is available through cellular respiration.Food energy is expressed in food calories or kilojoules...

     intake and a lack of physical activity is thought to explain most cases of obesity. A limited number of cases are due primarily to genetics, medical reasons, or psychiatric illness. In contrast, increasing rates of obesity at a societal level are felt to be due to an easily accessible and palatable diet, increased reliance on cars, and mechanized manufacturing.

    A 2006 review identified ten other possible contributors to the recent increase of obesity: (1) insufficient sleep, (2) endocrine disruptor
    Endocrine disruptor
    Endocrine disruptors are chemicals that interfere with endocrine in animals, including humans. These disruptions can cause cancerous tumors, birth defects, and other developmental disorders...

    s (environmental pollutant
    Pollutant
    A pollutant is a waste material that pollutes air, water or soil, and is the cause of pollution.Three factors determine the severity of a pollutant: its chemical nature, its concentration and its persistence. Some pollutants are biodegradable and therefore will not persist in the environment in the...

    s that interfere with lipid metabolism), (3) decreased variability in ambient temperature, (4) decreased rates of smoking
    Tobacco smoking
    Tobacco smoking is the practice where tobacco is burned and the resulting smoke is inhaled. The practice may have begun as early as 5000–3000 BCE. Tobacco was introduced to Eurasia in the late 16th century where it followed common trade routes...

    , because smoking suppresses appetite, (5) increased use of medications that can cause weight gain (e.g., atypical antipsychotics), (6) proportional increases in ethnic and age groups that tend to be heavier, (7) pregnancy at a later age (which may cause susceptibility to obesity in children), (8) epigenetic risk factors passed on generationally, (9) natural selection
    Natural selection
    Natural selection is the nonrandom process by which biologic traits become either more or less common in a population as a function of differential reproduction of their bearers. It is a key mechanism of evolution....

     for higher BMI, and (10) assortative mating
    Assortative mating
    Assortative mating , and the related concept Disassortative mating, is the phenomenon where a sexually reproducing organism chooses to mate with individuals that are similar or dissimilar to itself in some specific manner...

     leading to increased concentration of obesity risk factors (this would increase the number of obese people by increasing population variance in weight). While there is substantial evidence supporting the influence of these mechanisms on the increased prevalence of obesity, the evidence is still inconclusive, and the authors state that these are probably less influential than the ones discussed in the previous paragraph.

    Diet

    The per capita dietary energy supply
    Dietary energy supply
    The dietary energy supply is the food available for human consumption, usually expressed in kilocalories per person per day. It gives an overestimate of the total amount of food consumed as it reflects both food consumed and food wasted. It varies markedly between different regions and countries...

     varies markedly between different regions and countries. It has also changed significantly over time. From the early 1970s to the late 1990s the average calories available per person per day (the amount of food bought) increased in all parts of the world except Eastern Europe. The United States had the highest availability with 3,654 calories per person in 1996. This increased further in 2003 to 3,754. During the late 1990s Europeans had 3,394 calories per person, in the developing areas of Asia there were 2,648 calories per person, and in sub-Saharan Africa people had 2,176 calories per person. Total calorie consumption has been found to be related to obesity.

    The widespread availability of nutritional guidelines has done little to address the problems of overeating and poor dietary choice. From 1971 to 2000, obesity rates in the United States increased from 14.5% to 30.9%. During the same period, an increase occurred in the average amount of food energy consumed. For women, the average increase was 335 calories per day (1,542 calories in 1971 and 1,877 calories in 2004), while for men the average increase was 168 calories per day (2,450 calories in 1971 and 2,618 calories in 2004). Most of this extra food energy came from an increase in carbohydrate consumption rather than fat consumption. The primary sources of these extra carbohydrates are sweetened beverages, which now account for almost 25 percent of daily food energy in young adults in America, and potato chips. Consumption of sweetened drinks is believed to be contributing to the rising rates of obesity.

    As societies become increasingly reliant on energy-dense
    Food energy
    Food energy is the amount of energy obtained from food that is available through cellular respiration.Food energy is expressed in food calories or kilojoules...

    , big-portions, and fast-food meals, the association between fast-food consumption and obesity becomes more concerning. In the United States consumption of fast-food meals tripled and food energy intake from these meals quadrupled between 1977 and 1995.

    Agricultural policy
    Agricultural policy
    Agricultural policy describes a set of laws relating to domestic agriculture and imports of foreign agricultural products. Governments usually implement agricultural policies with the goal of achieving a specific outcome in the domestic agricultural product markets...

     and techniques in the United States and Europe have led to lower food prices. In the United States, subsidization of corn, soy, wheat, and rice through the U.S. farm bill
    U.S. farm bill
    In the United States, the farm bill is the primary agricultural and food policy tool of the federal government. The comprehensive omnibus bill is passed every 5 years or so by the United States Congress and deals with both agriculture and all other affairs under the purview of the United States...

     has made the main sources of processed food cheap compared to fruits and vegetables.

    Obese people consistently under-report their food consumption as compared to people of normal weight. This is supported both by tests of people carried out in a calorimeter
    Calorimeter
    A calorimeter is a device used for calorimetry, the science of measuring the heat of chemical reactions or physical changes as well as heat capacity. Differential scanning calorimeters, isothermal microcalorimeters, titration calorimeters and accelerated rate calorimeters are among the most common...

     room and by direct observation.

    Sedentary lifestyle

    A sedentary lifestyle
    Sedentary lifestyle
    Sedentary lifestyle is a medical term used to denote a type of lifestyle with no or irregular physical activity. A person who lives a sedentary lifestyle may colloquially be known as a couch potato. It is commonly found in both the developed and developing world...

     plays a significant role in obesity. Worldwide there has been a large shift towards less physically demanding work, and currently at least 60% of the world's population gets insufficient exercise. This is primarily due to increasing use of mechanized transportation and a greater prevalence of labor-saving technology in the home. In children, there appear to be declines in levels of physical activity due to less walking and physical education. World trends in active leisure time physical activity are less clear. The World Health Organization
    World Health Organization
    The World Health Organization is a specialized agency of the United Nations that acts as a coordinating authority on international public health. Established on 7 April 1948, with headquarters in Geneva, Switzerland, the agency inherited the mandate and resources of its predecessor, the Health...

     indicates people worldwide are taking up less active recreational pursuits, while a study from Finland found an increase and a study from the United States found leisure-time physical activity has not changed significantly.

    In both children and adults, there is an association between television viewing time and the risk of obesity. A 2008 meta-analysis found 63 of 73 studies (86%) showed an increased rate of childhood obesity with increased media exposure, with rates increasing proportionally to time spent watching television.

    Genetics

    Like many other medical conditions, obesity is the result of an interplay between genetic and environmental factors. Polymorphism
    Polymorphism (biology)
    Polymorphism in biology occurs when two or more clearly different phenotypes exist in the same population of a species — in other words, the occurrence of more than one form or morph...

    s in various gene
    Gene
    A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...

    s controlling appetite
    Appetite
    The appetite is the desire to eat food, felt as hunger. Appetite exists in all higher life-forms, and serves to regulate adequate energy intake to maintain metabolic needs. It is regulated by a close interplay between the digestive tract, adipose tissue and the brain. Decreased desire to eat is...

     and metabolism
    Metabolism
    Metabolism is the set of chemical reactions that happen in the cells of living organisms to sustain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments. Metabolism is usually divided into two categories...

     predispose to obesity when sufficient food energy present. As of 2006 more than 41 of these sites have been linked to the development of obesity when a favorable environment is present. People with two copies of the FTO gene
    FTO gene
    Fat mass and obesity-associated protein also known as alpha-ketoglutarate-dependent dioxygenase FTO is an enzyme that in humans is encoded by the FTO gene located on chromosome 16...

     (fat mass and obesity associated gene) has been found on average to weigh 3–4 kg more and have a 1.67-fold greater risk of obesity compared to those without the risk allele
    Allele
    An allele is one of two or more forms of a gene or a genetic locus . "Allel" is an abbreviation of allelomorph. Sometimes, different alleles can result in different observable phenotypic traits, such as different pigmentation...

    . The percentage of obesity that can be attributed to genetics varies, depending on the population examined, from 6% to 85%.

    Obesity is a major feature in several syndromes, such as Prader-Willi syndrome
    Prader-Willi syndrome
    Prader–Willi syndrome is a rare genetic disorder in which seven genes on chromosome 15 are deleted or unexpressed on the paternal chromosome...

    , Bardet-Biedl syndrome
    Bardet-Biedl syndrome
    The Bardet–Biedl syndrome is a ciliopathic human genetic disorder that produces many effects and affects many body systems. It is characterized principally by obesity, retinitis pigmentosa, polydactyly, mental retardation, hypogonadism, and renal failure in some cases.-Summary of the...

    , Cohen syndrome
    Cohen syndrome
    Cohen syndrome is believed to be a gene mutation at locus 8q22 gene COH1. Cohen syndrome has several characteristics such as obesity, mental retardation and craniofacial dysmorphism...

    , and MOMO syndrome
    MOMO syndrome
    MOMO syndrome is an extremely rare genetic disorder which belongs to the overgrowth syndromes and has been diagnosed in only six cases around the world, and occurs in 1 in 100 million births. The name is an acronym of the four primary aspects of the disorder: Macrosomia , Obesity, Macrocephaly and...

    . (The term "non-syndromic obesity" is sometimes used to exclude these conditions.) In people with early-onset severe obesity (defined by an onset before 10 years of age and body mass index over three standard deviation
    Standard deviation
    Standard deviation is a widely used measure of variability or diversity used in statistics and probability theory. It shows how much variation or "dispersion" there is from the average...

    s above normal), 7% harbor a single point DNA mutation.

    Studies that have focused upon inheritance patterns rather than upon specific genes have found that 80% of the offspring of two obese parents were obese, in contrast to less than 10% of the offspring of two parents who were of normal weight.

    The thrifty gene hypothesis
    Thrifty gene hypothesis
    The thrifty gene hypothesis was proposed by geneticist James V. Neel in 1962 to resolve a fundamental problem. Diabetes is clearly a very harmful medical condition. Yet it is quite common, and it was already evident to Neel that it likely had a strong genetic basis...

     postulates that due to dietary scarcity during human evolution people are prone to obesity. Their ability to take advantage of rare periods of abundance by storing energy as fat would be advantageous during times of varying food availability, and individuals with greater adipose reserves would be more likely survive famine
    Famine
    A famine is a widespread scarcity of food, caused by several factors including crop failure, overpopulation, or government policies. This phenomenon is usually accompanied or followed by regional malnutrition, starvation, epidemic, and increased mortality. Every continent in the world has...

    . This tendency to store fat, however, would be maladaptive in societies with stable food supplies. This theory has received various criticisms and other evolutionarily based theories such as the drifty gene hypothesis
    Drifty gene hypothesis
    The “”Drifty gene hypothesis”” was proposed by the British biologist John Speakman as an alternative to the thrifty gene hypothesis originally proposed by James V Neel in 1962...

     and the thrifty phenotype hypothesis
    Thrifty phenotype
    The thrifty phenotype hypothesis says that reduced fetal growth is strongly associated with a number of chronic conditions later in life. This increased susceptibility results from adaptations made by the fetus in an environment limited in its supply of nutrients...

     have also been proposed.

    Medical and psychiatric illness

    Certain physical and mental illnesses and the pharmaceutical substances used to treat them can increase risk of obesity. Medical illnesses that increase obesity risk include several rare genetic syndromes (listed above) as well as some congenital or acquired conditions: hypothyroidism
    Hypothyroidism
    Hypothyroidism is a condition in which the thyroid gland does not make enough thyroid hormone.Iodine deficiency is the most common cause of hypothyroidism worldwide but it can be caused by other causes such as several conditions of the thyroid gland or, less commonly, the pituitary gland or...

    , Cushing's syndrome
    Cushing's syndrome
    Cushing's syndrome is a hormone disorder caused by high levels of cortisol in the blood. This can be caused by taking glucocorticoid drugs, or by tumors that produce cortisol or adrenocorticotropic hormone or CRH...

    , growth hormone deficiency
    Growth hormone deficiency
    Growth hormone deficiency is a medical condition in which the body does not produce enough growth hormone . Growth hormone, also called somatotropin, is a polypeptide hormone which stimulates growth and cell reproduction...

    , and the eating disorder
    Eating disorder
    Eating disorders refer to a group of conditions defined by abnormal eating habits that may involve either insufficient or excessive food intake to the detriment of an individual's physical and mental health. Bulimia nervosa, anorexia nervosa, and binge eating disorder are the most common specific...

    s: binge eating disorder
    Binge eating disorder
    Binge eating disorder is the most common eating disorder in the United States affecting 3.5% of females and 2% of males and is prevalent in up to 30% of those seeking weight loss treatment...

     and night eating syndrome
    Night eating syndrome
    Night eating syndrome, or NES, is an emerging eating disorder diagnosis, which primarily characterizes an ongoing, persistent pattern of late-night binge eating....

    . However, obesity is not regarded as a psychiatric disorder, and therefore is not listed in the DSM-IVR
    Diagnostic and Statistical Manual of Mental Disorders
    The Diagnostic and Statistical Manual of Mental Disorders is published by the American Psychiatric Association and provides a common language and standard criteria for the classification of mental disorders...

     as a psychiatric illness. The risk of overweight and obesity is higher in patients with psychiatric disorders than in persons without psychiatric disorders.

    Certain medications may cause weight gain or changes in body composition
    Body composition
    In physical fitness, body composition is used to describe the percentages of fat, bone and muscle in human bodies. Because muscular tissue takes up less space in our body than fat tissue, our body composition, as well as our weight, determines leanness...

    ; these include insulin
    Insulin
    Insulin is a hormone central to regulating carbohydrate and fat metabolism in the body. Insulin causes cells in the liver, muscle, and fat tissue to take up glucose from the blood, storing it as glycogen in the liver and muscle....

    , sulfonylurea
    Sulfonylurea
    Sulfonylurea derivatives are a class of antidiabetic drugs that are used in the management of diabetes mellitus type 2. They act by increasing insulin release from the beta cells in the pancreas.-First generation:* Carbutamide...

    s, thiazolidinedione
    Thiazolidinedione
    The thiazolidinediones , also known as glitazones, are a class of medications used in the treatment of diabetes mellitus type 2. They were introduced in the late 1990s.- Mechanism of action :...

    s, atypical antipsychotic
    Atypical antipsychotic
    The atypical antipsychotics are a group of antipsychotic tranquilizing drugs used to treat psychiatric conditions. Some atypical antipsychotics are FDA approved for use in the treatment of schizophrenia...

    s, antidepressant
    Antidepressant
    An antidepressant is a psychiatric medication used to alleviate mood disorders, such as major depression and dysthymia and anxiety disorders such as social anxiety disorder. According to Gelder, Mayou &*Geddes people with a depressive illness will experience a therapeutic effect to their mood;...

    s, steroids, certain anticonvulsant
    Anticonvulsant
    The anticonvulsants are a diverse group of pharmaceuticals used in the treatment of epileptic seizures. Anticonvulsants are also increasingly being used in the treatment of bipolar disorder, since many seem to act as mood stabilizers, and in the treatment of neuropathic pain. The goal of an...

    s (phenytoin
    Phenytoin
    Phenytoin sodium is a commonly used antiepileptic. Phenytoin acts to suppress the abnormal brain activity seen in seizure by reducing electrical conductance among brain cells by stabilizing the inactive state of voltage-gated sodium channels...

     and valproate), pizotifen
    Pizotifen
    Pizotifen or pizotyline , trade name Sandomigran, is a benzocycloheptene based drug used as a medicine, primarily as a preventative to reduce the frequency of recurrent migraine headaches.-Uses:...

    , and some forms of hormonal contraception
    Hormonal contraception
    Hormonal contraception refers to birth control methods that act on the endocrine system. Almost all methods are composed of steroid hormones, although in India one selective estrogen receptor modulator is marketed as a contraceptive. The original hormonal method—the combined oral contraceptive...

    .

    Social determinants

    While genetic influences are important to understanding obesity, they cannot explain the current dramatic increase seen within specific countries or globally. Though it is accepted that energy consumption in excess of energy expenditure leads to obesity on an individual basis, the cause of the shifts in these two factors on the societal scale is much debated. There are a number of theories as to the cause but most believe it is a combination of various factors.

    The correlation between social class
    Social class
    Social classes are economic or cultural arrangements of groups in society. Class is an essential object of analysis for sociologists, political scientists, economists, anthropologists and social historians. In the social sciences, social class is often discussed in terms of 'social stratification'...

     and BMI varies globally. A review in 1989 found that in developed countries women of a high social class were less likely to be obese. No significant differences were seen among men of different social classes. In the developing world, women, men, and children from high social classes had greater rates of obesity. An update of this review carried out in 2007 found the same relationships, but they were weaker. The decrease in strength of correlation was felt to be due to the effects of globalization
    Globalization
    Globalization refers to the increasingly global relationships of culture, people and economic activity. Most often, it refers to economics: the global distribution of the production of goods and services, through reduction of barriers to international trade such as tariffs, export fees, and import...

    . Among developed countries, levels of adult obesity, and percentage of teenage children who are overweight, are correlated with income inequality
    Economic inequality
    Economic inequality comprises all disparities in the distribution of economic assets and income. The term typically refers to inequality among individuals and groups within a society, but can also refer to inequality among countries. The issue of economic inequality is related to the ideas of...

    . A similar relationship is seen among US states: more adults, even in higher social classes, are obese in more unequal states.

    Many explanations have been put forth for associations between BMI and social class. It is thought that in developed countries, the wealthy are able to afford more nutritious food, they are under greater social pressure to remain slim, and have more opportunities along with greater expectations for physical fitness
    Physical fitness
    Physical fitness comprises two related concepts: general fitness , and specific fitness...

    . In undeveloped countries the ability to afford food, high energy expenditure with physical labor, and cultural values favoring a larger body size are believed to contribute to the observed patterns. Attitudes toward body mass held by people in one's life may also play a role in obesity. A correlation in BMI changes over time has been found among friends, siblings, and spouses. Stress and perceived low social status appear to increase risk of obesity.

    Smoking has a significant effect on an individual's weight. Those who quit smoking gain an average of 4.4 kilograms (9.7 lb) for men and 5.0 kilograms (11.0 lb) for women over ten years. However, changing rates of smoking have had little effect on the overall rates of obesity.

    In the United States the number of children a person has is related to their risk of obesity. A woman's risk increases by 7% per child, while a man's risk increases by 4% per child. This could be partly explained by the fact that having dependent children decreases physical activity in Western parents.

    In the developing world urbanization is playing a role in increasing rate of obesity. In China
    China
    Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...

     overall rates of obesity are below 5%; however, in some cities rates of obesity are greater than 20%.

    Malnutrition
    Malnutrition
    Malnutrition is the condition that results from taking an unbalanced diet in which certain nutrients are lacking, in excess , or in the wrong proportions....

     in early life is believed to play a role in the rising rates of obesity in the developing world. Endocrine changes that occur during periods of malnutrition may promote the storage of fat once more food energy becomes available.

    Consistent with cognitive epidemiological
    Cognitive epidemiology
    Cognitive epidemiology is a field of research that examines the associations between intelligence test scores and health, more specifically morbidity and mortality. Typically, test scores are obtained at an early age, and compared to later morbidity and mortality...

     data, numerous studies confirm that obesity is associated with cognitive deficits. Whether obesity causes cognitive deficits, or vice versa is unclear at present.

    Infectious agents

    The study of the effect of infectious agents on metabolism is still in its early stages. Gut flora
    Gut flora
    Gut flora consists of microorganisms that live in the digestive tracts of animals and is the largest reservoir of human flora. In this context, gut is synonymous with intestinal, and flora with microbiota and microflora....

     has been shown to differ between lean and obese humans. There is an indication that gut flora in obese and lean individuals can affect the metabolic potential. This apparent alteration of the metabolic potential is believed to confer a greater capacity to harvest energy contributing to obesity. Whether these differences are the direct cause or the result of obesity has yet to be determined unequivocally.

    An association between viruses and obesity has been found in humans and several different animal species. The amount that these associations may have contributed to the rising rate of obesity is yet to be determined.

    Pathophysiology

    Flier summarizes the many possible pathophysiological
    Pathophysiology
    Pathophysiology is the study of the changes of normal mechanical, physical, and biochemical functions, either caused by a disease, or resulting from an abnormal syndrome...

     mechanisms involved in the development and maintenance of obesity. This field of research had been almost unapproached until leptin
    Leptin
    Leptin is a 16 kDa protein hormone that plays a key role in regulating energy intake and energy expenditure, including appetite and metabolism. It is one of the most important adipose derived hormones...

     was discovered in 1994. Since this discovery, many other hormonal mechanisms have been elucidated that participate in the regulation of appetite
    Appetite
    The appetite is the desire to eat food, felt as hunger. Appetite exists in all higher life-forms, and serves to regulate adequate energy intake to maintain metabolic needs. It is regulated by a close interplay between the digestive tract, adipose tissue and the brain. Decreased desire to eat is...

     and food intake, storage patterns of adipose tissue
    Adipose tissue
    In histology, adipose tissue or body fat or fat depot or just fat is loose connective tissue composed of adipocytes. It is technically composed of roughly only 80% fat; fat in its solitary state exists in the liver and muscles. Adipose tissue is derived from lipoblasts...

    , and development of insulin resistance
    Insulin resistance
    Insulin resistance is a physiological condition where the natural hormone insulin becomes less effective at lowering blood sugars. The resulting increase in blood glucose may raise levels outside the normal range and cause adverse health effects, depending on dietary conditions. Certain cell types...

    . Since leptin's discovery, ghrelin
    Ghrelin
    Ghrelin is a 28 amino acid peptide and hormone that is produced mainly by P/D1 cells lining the fundus of the human stomach and epsilon cells of the pancreas that stimulates hunger. Ghrelin levels increase before meals and decrease after meals. It is considered the counterpart of the hormone...

    , insulin
    Insulin
    Insulin is a hormone central to regulating carbohydrate and fat metabolism in the body. Insulin causes cells in the liver, muscle, and fat tissue to take up glucose from the blood, storing it as glycogen in the liver and muscle....

    , orexin
    Orexin
    Orexins, also called hypocretins, are the common names given to a pair of excitatory neuropeptide hormones that were simultaneously discovered by two groups of researchers in rat brains....

    , PYY 3-36, cholecystokinin
    Cholecystokinin
    Cholecystokinin is a peptide hormone of the gastrointestinal system responsible for stimulating the digestion of fat and protein...

    , adiponectin
    Adiponectin
    Adiponectin is a protein which in humans is encoded by the ADIPOQ gene.- Structure :...

    , as well as many other mediators have been studied. The adipokine
    Adipokine
    The adipokines or adipocytokines are cytokines secreted by adipose tissue.Members include:* chemerin* interleukin-6...

    s are mediators produced by adipose tissue; their action is thought to modify many obesity-related diseases.

    Leptin and ghrelin are considered to be complementary in their influence on appetite, with ghrelin produced by the stomach modulating short-term appetitive control (i.e. to eat when the stomach is empty and to stop when the stomach is stretched). Leptin is produced by adipose tissue to signal fat storage reserves in the body, and mediates long-term appetitive controls (i.e. to eat more when fat storages are low and less when fat storages are high). Although administration of leptin may be effective in a small subset of obese individuals who are leptin deficient, most obese individuals are thought to be leptin resistant and have been found to have high levels of leptin. This resistance is thought to explain in part why administration of leptin has not been shown to be effective in suppressing appetite in most obese people.

    While leptin and ghrelin are produced peripherally, they control appetite through their actions on the central nervous system
    Central nervous system
    The central nervous system is the part of the nervous system that integrates the information that it receives from, and coordinates the activity of, all parts of the bodies of bilaterian animals—that is, all multicellular animals except sponges and radially symmetric animals such as jellyfish...

    . In particular, they and other appetite-related hormones act on the hypothalamus
    Hypothalamus
    The Hypothalamus is a portion of the brain that contains a number of small nuclei with a variety of functions...

    , a region of the brain central to the regulation of food intake and energy expenditure. There are several circuits within the hypothalamus that contribute to its role in integrating appetite, the melanocortin
    Melanocortin
    The melanocortins are a group of peptide hormones which include adrenocorticotropic hormone and the different forms of melanocyte-stimulating hormone . They can be synthetic . In humans they can be endogenously produced from proopiomelanocortin in the pituitary gland...

     pathway being the most well understood. The circuit begins with an area of the hypothalamus, the arcuate nucleus
    Arcuate nucleus
    The arcuate nucleus is an aggregation of neurons in the mediobasal hypothalamus, adjacent to the third ventricle and the median eminence...

    , that has outputs to the lateral hypothalamus
    Lateral hypothalamus
    The lateral hypothalamus or lateral hypothalamic area is a part of the hypothalamus.It is concerned with hunger. Damage to this area can cause reduced food intake...

     (LH) and ventromedial hypothalamus (VMH), the brain's feeding and satiety centers, respectively.

    The arcuate nucleus contains two distinct groups of neuron
    Neuron
    A neuron is an electrically excitable cell that processes and transmits information by electrical and chemical signaling. Chemical signaling occurs via synapses, specialized connections with other cells. Neurons connect to each other to form networks. Neurons are the core components of the nervous...

    s. The first group coexpresses neuropeptide Y
    Neuropeptide Y
    Neuropeptide Y is a 36-amino acid peptide neurotransmitter found in the brain and autonomic nervous system."NPY has been associated with a number of physiologic processes in the brain, including the regulation of energy balance, memory and learning, and epilepsy." The main effect is increased food...

     (NPY) and agouti-related peptide
    Agouti-related peptide
    Agouti-related protein also called Agouti-related peptide is a neuropeptide produced in the brain by the AgRP/NPY neuron. It is only synthesised in NPY containing cell bodies located in the ventromedial part of the arcuate nucleus in the hypothalamus...

     (AgRP) and has stimulatory inputs to the LH and inhibitory inputs to the VMH. The second group coexpresses pro-opiomelanocortin (POMC) and cocaine- and amphetamine-regulated transcript
    Cocaine- and amphetamine-regulated transcript
    Cocaine and amphetamine regulated transcript also known as CART is a protein that in humans is encoded by the CARTPT gene. CART appears to have roles in reward, feeding, and stress, and it has the functional properties of an endogenous psychostimulant.- Function :CART is a neuropeptide that also...

     (CART) and has stimulatory inputs to the VMH and inhibitory inputs to the LH. Consequently, NPY/AgRP neurons stimulate feeding and inhibit satiety, while POMC/CART neurons stimulate satiety and inhibit feeding. Both groups of arcuate nucleus neurons are regulated in part by leptin. Leptin inhibits the NPY/AgRP group while stimulating the POMC/CART group. Thus a deficiency in leptin signaling, either via leptin deficiency or leptin resistance, leads to overfeeding and may account for some genetic and acquired forms of obesity.

    Public health

    The World Health Organization
    World Health Organization
    The World Health Organization is a specialized agency of the United Nations that acts as a coordinating authority on international public health. Established on 7 April 1948, with headquarters in Geneva, Switzerland, the agency inherited the mandate and resources of its predecessor, the Health...

     (WHO) predicts that overweight
    Overweight
    Overweight is generally defined as having more body fat than is optimally healthy. Being overweight is a common condition, especially where food supplies are plentiful and lifestyles are sedentary...

     and obesity may soon replace more traditional public health
    Public health
    Public health is "the science and art of preventing disease, prolonging life and promoting health through the organized efforts and informed choices of society, organizations, public and private, communities and individuals" . It is concerned with threats to health based on population health...

     concerns such as undernutrition and infectious diseases as the most significant cause of poor health. Obesity is a public health and policy problem because of its prevalence, costs, and health effects.
    Public health efforts seek to understand and correct the environmental factors responsible for the increasing prevalence of obesity in the population. Solutions look at changing the factors that cause excess food energy consumption and inhibit physical activity. Efforts include federally reimbursed meal programs in schools, limiting direct junk food
    Junk food
    Junk food is an informal term applied to some foods that are perceived to have little or no nutritional value ; to products with nutritional value, but which also have ingredients considered unhealthy when regularly eaten; or to those considered unhealthy to consume at all...

     marketing to children, and decreasing access to sugar-sweetened beverages in schools. When constructing urban environments, efforts have been made to increase access to parks and to develop pedestrian routes.

    Many countries and groups have published reports pertaining to obesity. In 1998 the first US Federal guidelines were published, titled "Clinical Guidelines on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults: The Evidence Report". In 2006 the Canadian Obesity Network
    Canadian Obesity Network
    The Canadian Obesity Network-Réseau Canadien en l’Obésité is the primary Canadian network of obesity researchers, health professionals and others with a professional interest in obesity. In Canada, like in many other parts of the world, obesity funding, research, prevention and treatment...

     published the "Canadian Clinical Practice Guidelines (CPG) on the Management and Prevention of Obesity in Adults and Children". This is a comprehensive evidence-based guideline to address the management and prevention of overweight and obesity in adults and children.

    In 2004, the United Kingdom Royal College of Physicians
    Royal College of Physicians
    The Royal College of Physicians of London was founded in 1518 as the College of Physicians by royal charter of King Henry VIII in 1518 - the first medical institution in England to receive a royal charter...

    , the Faculty of Public Health
    Faculty of Public Health
    The Faculty of Public Health is the standard setting body for specialists in public health in the United Kingdom.The Faculty of Public Health was formed in 1972 by the three Royal Colleges of Physicians of the United Kingdom .The Faculty seeks to promote public...

     and the Royal College of Paediatrics and Child Health
    Royal College of Paediatrics and Child Health
    Royal College of Paediatrics and Child Health in London is responsible for the training of postgraduate doctors in paediatrics and conducting the MRCPCH membership exams. They also conduct the Diploma in Child Health exam, which is taken by many doctors who plan a career in General Practice...

     released the report "Storing up Problems", which highlighted the growing problem of obesity in the UK. The same year, the House of Commons
    British House of Commons
    The House of Commons is the lower house of the Parliament of the United Kingdom, which also comprises the Sovereign and the House of Lords . Both Commons and Lords meet in the Palace of Westminster. The Commons is a democratically elected body, consisting of 650 members , who are known as Members...

     Health Select Committee
    Health Select Committee
    The Health Select Committee is one of the Select Committees of the British House of Commons. It oversees the operations of the Department of Health and its associated bodies.-Membership:...

     published its "most comprehensive inquiry [...] ever undertaken" into the impact of obesity on health and society in the UK and possible approaches to the problem. In 2006, the National Institute for Health and Clinical Excellence
    National Institute for Health and Clinical Excellence
    The National Institute for Health and Clinical Excellence is a special health authority of the English National Health Service , serving both English NHS and the Welsh NHS...

     (NICE) issued a guideline on the diagnosis and management of obesity, as well as policy implications for non-healthcare organizations such as local councils.

    A 2007 report produced by Sir Derek Wanless
    Derek Wanless
    Sir Derek Wanless is an English banker and adviser to the United Kingdom Government.He was educated at the Royal Grammar School in Newcastle, has an MA in Mathematics from King's College, Cambridge which he attended on a support grant from Westminster Bank...

     for the King's Fund
    King's Fund
    The King's Fund is a charitable foundation in England. Founded as the Prince of Wales Hospital Fund for London in 1897, the fund changed its name in 1902 to King Edward's Hospital Fund after the accession to the throne of King Edward VII...

     warned that unless further action was taken, obesity had the capacity to cripple the National Health Service
    National Health Service
    The National Health Service is the shared name of three of the four publicly funded healthcare systems in the United Kingdom. They provide a comprehensive range of health services, the vast majority of which are free at the point of use to residents of the United Kingdom...

     financially. In the United States organizations such as the Bill Clinton Foundation's Alliance for a Healthier Generation and Action for Healthy Kids
    Action for Healthy Kids
    Action for Healthy Kids is a public-private partnership of more than 50 organizations dedicated to promoting school health. Founded in 2002, the organization addresses the epidemic of overweight, sedentary, and undernourished youth by focusing on changes in schools to improve nutrition and increase...

     are working to combat childhood obesity. Additionally, the Centers for Disease Control and Prevention
    Centers for Disease Control and Prevention
    The Centers for Disease Control and Prevention are a United States federal agency under the Department of Health and Human Services headquartered in Druid Hills, unincorporated DeKalb County, Georgia, in Greater Atlanta...

     co-hosted the first-ever Weight of the Nation Conference in 2009 with the goal of focusing national attention on the obesity epidemic.

    Comprehensive approaches are being looked at to address the rising rates of obesity. The Obesity Policy Action (OPA) framework divides measure into 'upstream' policies, 'midstream' policies, 'downstream' policies. 'Upstream' policies look at changing society, 'midstream' policies try to alter individuals' behavior to prevent obesity, and 'downstream' policies try to treat currently afflicted people.

    Management

    The main treatment for obesity consists of dieting
    Dieting
    Dieting is the practice of eating food in a regulated fashion to achieve or maintain a controlled weight. In most cases dieting is used in combination with physical exercise to lose weight in those who are overweight or obese. Some athletes, however, follow a diet to gain weight...

     and physical exercise
    Physical exercise
    Physical exercise is any bodily activity that enhances or maintains physical fitness and overall health and wellness. It is performed for various reasons including strengthening muscles and the cardiovascular system, honing athletic skills, weight loss or maintenance, as well as for the purpose of...

    . Diet programs may produce weight loss
    Weight loss
    Weight loss, in the context of medicine, health or physical fitness, is a reduction of the total body mass, due to a mean loss of fluid, body fat or adipose tissue and/or lean mass, namely bone mineral deposits, muscle, tendon and other connective tissue...

     over the short term, but maintaining this weight loss is frequently difficult and often requires making exercise and a lower food energy diet a permanent part of a person's lifestyle. Success rates of long-term weight loss maintenance with lifestyle changes are low ranging from 2–20%.

    One medication, orlistat
    Orlistat
    Orlistat , also known as tetrahydrolipstatin, is a drug designed to treat obesity. Its primary function is preventing the absorption of fats from the human diet, thereby reducing caloric intake...

     (Xenical), is current widely available and approved for long term use. Weight loss however is modest with an average of 2.9 kg (6.4 lb) at 1 to 4 years and there is little information on how these drugs affect longer-term complications of obesity. It use is associated with high rates of gastrointestinal side effects and concerns have been raised about negative effects on the kidneys.

    The most effective treatment for obesity is bariatric surgery
    Bariatric surgery
    Bariatric surgery includes a variety of procedures performed on people who are obese. Weight loss is achieved by reducing the size of the stomach with an implanted medical device or through removal of a portion of the stomach or by resecting and re-routing the small intestines...

    . Surgery for severe obesity is associated with long-term weight loss and decreased overall mortality. One study found a weight loss of between 14% and 25% (depending on the type of procedure performed) at 10 years, and a 29% reduction in all cause mortality when compared to standard weight loss measures. However, due to its cost and the risk of complications, researchers are searching for other effective yet less invasive treatments.

    Epidemiology

    Before the 20th century, obesity was rare; in 1997 the WHO formally recognized obesity as a global epidemic. As of 2005 the WHO estimates that at least 400 million adults (9.8%) are obese, with higher rates among women than men. The rate of obesity also increases with age at least up to 50 or 60 years old and severe obesity in the United States, Australia, and Canada is increasing faster than the overall rate of obesity.

    Once considered a problem only of high-income countries, obesity rates are rising worldwide and affecting both the developed and developing world. These increases have been felt most dramatically in urban settings. The only remaining region of the world where obesity is not common is sub-Saharan Africa
    Sub-Saharan Africa
    Sub-Saharan Africa as a geographical term refers to the area of the African continent which lies south of the Sahara. A political definition of Sub-Saharan Africa, instead, covers all African countries which are fully or partially located south of the Sahara...

    .

    Etymology

    Obesity is from the Latin
    Latin
    Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...

     obesitas, which means "stout, fat, or plump." Ēsus is the past participle of edere (to eat), with ob (over) added to it. The Oxford English Dictionary documents its first usage in 1611 by Randle Cotgrave
    Randle Cotgrave
    Randle Cotgrave , may possibly be Randal, son of William Cotgreve of Christleton in Cheshire, who is mentioned in the pedigree of the Cotgreve family, contained in Harl. MS. 1500, fol...

    .

    Historical trends

    The Greeks
    Greeks
    The Greeks, also known as the Hellenes , are a nation and ethnic group native to Greece, Cyprus and neighboring regions. They also form a significant diaspora, with Greek communities established around the world....

     were the first to recognize obesity as a medical disorder. Hippocrates
    Hippocrates
    Hippocrates of Cos or Hippokrates of Kos was an ancient Greek physician of the Age of Pericles , and is considered one of the most outstanding figures in the history of medicine...

     wrote that "Corpulence is not only a disease itself, but the harbinger of others". The Indian surgeon Sushruta (6th century BCE) related obesity to diabetes and heart disorders. He recommended physical work to help cure it and its side effects. For most of human history mankind struggled with food scarcity. Obesity has thus historically been viewed as a sign of wealth and prosperity. It was common among high officials in Europe in the Middle Ages
    Middle Ages
    The Middle Ages is a periodization of European history from the 5th century to the 15th century. The Middle Ages follows the fall of the Western Roman Empire in 476 and precedes the Early Modern Era. It is the middle period of a three-period division of Western history: Classic, Medieval and Modern...

     and the Renaissance
    Renaissance
    The Renaissance was a cultural movement that spanned roughly the 14th to the 17th century, beginning in Italy in the Late Middle Ages and later spreading to the rest of Europe. The term is also used more loosely to refer to the historical era, but since the changes of the Renaissance were not...

     as well as in Ancient East Asian civilizations.

    With the onset of the industrial revolution
    Industrial Revolution
    The Industrial Revolution was a period from the 18th to the 19th century where major changes in agriculture, manufacturing, mining, transportation, and technology had a profound effect on the social, economic and cultural conditions of the times...

     it was realized that the military and economic might of nations were dependent on both the body size and strength of their soldiers and workers. Increasing the average body mass index from what is now considered underweight to what is now the normal range played a significant role in the development of industrialized societies. Height and weight thus both increased through the 19th century in the developed world. During the 20th century, as populations reached their genetic potential for height, weight began increasing much more than height, resulting in obesity. In the 1950s increasing wealth in the developed world decreased child mortality, but as body weight increased heart and kidney disease became more common.
    During this time period insurance companies realized the connection between weight and life expectancy and increased premiums for the obese.

    Many cultures throughout history have viewed obesity as the result of a character flaw. The obesus or fat character in Greek comedy was a glutton and figure of mockery. During Christian times food was viewed as a gateway to the sins of sloth
    Sloth
    Sloths are the six species of medium-sized mammals belonging to the families Megalonychidae and Bradypodidae , part of the order Pilosa and therefore related to armadillos and anteaters, which sport a similar set of specialized claws.They are arboreal residents of the jungles of Central and South...

     and lust
    Lust
    Lust is an emotional force that is directly associated with the thinking or fantasizing about one's desire, usually in a sexual way.-Etymology:The word lust is phonetically similar to the ancient Roman lustrum, which literally meant "purification"...

    . In modern Western culture, excess weight is often regarded as unattractive, and obesity is commonly associated with various negative stereotypes. People of all ages can face social stigmatization, and may be targeted by bullies or shunned by their peers. Obesity is once again a reason for discrimination.

    Public perceptions in Western society regarding healthy body weight differ from those regarding the weight that is considered ideal  – and both have changed since the beginning of the 20th century. The weight that is viewed as an ideal has become lower since the 1920s. This is illustrated by the fact that the average height of Miss America pageant winners increased by 2% from 1922 to 1999, while their average weight decreased by 12%. On the other hand, people's views concerning healthy weight have changed in the opposite direction. In Britain the weight at which people considered themselves to be overweight was significantly higher in 2007 than in 1999. These changes are believed to be due to increasing rates of adiposity leading to increased acceptance of extra body fat as being normal.

    Obesity is still seen as a sign of wealth and well-being in many parts of Africa
    Africa
    Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...

    . This has become particularly common since the HIV
    HIV
    Human immunodeficiency virus is a lentivirus that causes acquired immunodeficiency syndrome , a condition in humans in which progressive failure of the immune system allows life-threatening opportunistic infections and cancers to thrive...

     epidemic began.

    The arts

    The first sculptural representations of the human body 20,000–35,000 years ago depict obese females. Some attribute the Venus figurines
    Venus figurines
    Venus figurines is an umbrella term for a number of prehistoric statuettes of women portrayed with similar physical attributes from the Upper Palaeolithic, mostly found in Europe, but with finds as far east as Irkutsk Oblast, Siberia, extending their distribution to much of Eurasia, from the...

     to the tendency to emphasize fertility while others feel they represent "fatness" in the people of the time. Corpulence is, however, absent in both Greek and Roman art, probably in keeping with their ideals regarding moderation. This continued through much of Christian European history, with only those of low socioeconomic status being depicted as obese.

    During the Renaissance
    Renaissance
    The Renaissance was a cultural movement that spanned roughly the 14th to the 17th century, beginning in Italy in the Late Middle Ages and later spreading to the rest of Europe. The term is also used more loosely to refer to the historical era, but since the changes of the Renaissance were not...

     some of the upper class began flaunting their large size, as can be seen in portraits of Henry the VIII and Alessandro del Borro. Rubens (1577–1640) regularly depicted full-bodied women in his pictures, from which derives the term Rubenesque. These women, however, still maintained the "hourglass" shape with its relationship to fertility. During the 19th century, views on obesity changed in the Western world. After centuries of obesity being synonymous with wealth and social status, slimness began to be seen as the desirable standard.

    Economic impact

    In addition to its health impacts, obesity leads to many problems including disadvantages in employment and increased business costs. These effects are felt by all levels of society from individuals, to corporations, to governments.

    The estimate range for annual expenditures on diet products is $40 billion to $100 billion in the US alone. In 1998, the medical costs attributable to obesity in the US were $78.5 billion or 9.1% of all medical expenditures, while the cost of obesity in Canada was estimated at CA$2 billion in 1997 (2.4% of total health costs).The total annual direct cost of overweight and obesity in Australia in 2005 was AUD $21 billion. Overweight and obese Australians also received AUD $35.6 billion in government subsidies.

    Obesity prevention programs have been found to reduce the cost of treating obesity-related disease. However, the longer people live, the more medical costs they incur. Researchers therefore conclude that reducing obesity may improve the public's health, but it is unlikely to reduce overall health spending.

    Obesity can lead to social stigmatization and disadvantages in employment. When compared to their normal weight counterparts, obese workers on average have higher rates of absenteeism from work and take more disability leave, thus increasing costs for employers and decreasing productivity. A study examining Duke University employees found that people with a BMI over 40 filed twice as many workers' compensation
    Workers' compensation
    Workers' compensation is a form of insurance providing wage replacement and medical benefits to employees injured in the course of employment in exchange for mandatory relinquishment of the employee's right to sue his or her employer for the tort of negligence...

     claims as those whose BMI was 18.5–24.9. They also had more than 12 times as many lost work days. The most common injuries in this group were due to falls and lifting, thus affecting the lower extremities, wrists or hands, and backs. The US state of Alabama Employees' Insurance Board approved a controversial plan to charge obese workers $25 per month if they do not take measures to reduce their weight and improve their health. These measures started in January 2010 and apply to those with a BMI of greater than 35 kg/m2 who fail to make improvements in their health after one year.

    Some research shows that obese people are less likely to be hired for a job and are less likely to be promoted. Obese people are also paid less than their non-obese counterparts for an equivalent job. Obese women on average make 6% less and obese men make 3% less.

    Specific industries, such as the airline and food industries, have special concerns. Due to rising rates of obesity, airlines face higher fuel costs and pressures to increase seating width. In 2000, the extra weight of obese passengers cost airlines US$275 million. Costs for restaurants are increased by litigation accusing them of causing obesity. In 2005 the US Congress discussed legislation to prevent civil law suits against the food industry in relation to obesity; however, it did not become law.

    Size acceptance

    The principal goal of the fat acceptance movement is to decrease discrimination against people who are overweight and obese. However, some in the movement are also attempting to challenge the established relationship between obesity and negative health outcomes.

    A number of organizations exist that promote the acceptance of obesity. They have increased in prominence in the latter half of the 20th century. The US-based National Association to Advance Fat Acceptance
    National Association to Advance Fat Acceptance
    The National Association to Advance Fat Acceptance is a non-profit civil-rights organization in the US dedicated to improving the quality of life for the obese...

     (NAAFA) was formed in 1969 and describes itself as a civil rights organization dedicated to ending size discrimination. However, fat activism remains a marginal movement.

    The International Size Acceptance Association
    International Size Acceptance Association
    The International Size Acceptance Association is a United States based non-governmental organization aimed at advancing Fat Acceptance, directed by Allen Steadham. Unlike National Association to Advance Fat Acceptance however, the organisation has an international slant, and has several overseas...

     (ISAA) is a non-governmental organization
    Non-governmental organization
    A non-governmental organization is a legally constituted organization created by natural or legal persons that operates independently from any government. The term originated from the United Nations , and is normally used to refer to organizations that do not form part of the government and are...

     (NGO) which was founded in 1997. It has more of a global orientation and describes its mission as promoting size acceptance and helping to end weight-based discrimination. These groups often argue for the recognition of obesity as a disability under the US Americans With Disabilities Act (ADA). The American legal system, however, has decided that the potential public health costs exceed the benefits of extending this anti-discrimination law to cover obesity.

    Childhood obesity

    The healthy BMI range varies with the age and sex of the child. Obesity in children and adolescents is defined as a BMI greater than the 95th percentile
    Percentile
    In statistics, a percentile is the value of a variable below which a certain percent of observations fall. For example, the 20th percentile is the value below which 20 percent of the observations may be found...

    . The reference data that these percentiles are based on is from 1963 to 1994 and thus has not been affected by the recent increases in rates of obesity. Childhood obesity has reached epidemic proportions in 21st century, with rising rates in both the developed and developing world. Rates of obesity in Canadian boys have increased from 11% in 1980s to over 30% in 1990s, while during this same time period rates increased from 4 to 14% in Brazilian children.

    As with obesity in adults, many different factors contribute to the rising rates of childhood obesity. Changing diet and decreasing physical activity are believed to be the two most important in causing the recent increase in the rates. Because childhood obesity often persists into adulthood and is associated with numerous chronic illnesses, children who are obese are often tested for hypertension
    Hypertension
    Hypertension or high blood pressure is a cardiac chronic medical condition in which the systemic arterial blood pressure is elevated. What that means is that the heart is having to work harder than it should to pump the blood around the body. Blood pressure involves two measurements, systolic and...

    , diabetes, hyperlipidemia
    Hyperlipidemia
    Hyperlipidemia, hyperlipoproteinemia, or hyperlipidaemia is the condition of abnormally elevated levels of any or all lipids and/or lipoproteins in the blood...

    , and fatty liver
    Fatty liver
    Fatty liver, also known as fatty liver disease , is a reversible condition where large vacuoles of triglyceride fat accumulate in liver cells via the process of steatosis...

    . Treatments used in children are primarily lifestyle interventions and behavioral techniques. In the United States, medications are not FDA approved for use in this age group.

    In other animals

    Obesity in pets is common in many countries. Rates of overweight and obesity in dogs in the United States range from 23% to 41% with about 5.1% obese. Rates of obesity in cats was slightly higher at 6.4%. In Australia the rate of obesity among dogs in a veterinary setting has been found to be 7.6%. The risk of obesity in dogs is related to whether or not their owners are obese; however, there is no similar correlation between cats and their owners.

    External links

    The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
     
    x
    OK