Estrogen dominance is a theory about a metabolic

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...

 state where the level of estrogen

Estrogen

Estrogens , oestrogens , or œstrogens, are a group of compounds named for their importance in the estrous cycle of humans and other animals. They are the primary female sex hormones. Natural estrogens are steroid hormones, while some synthetic ones are non-steroidal...

 outweighs the level of progesterone

Progesterone

Progesterone also known as P4 is a C-21 steroid hormone involved in the female menstrual cycle, pregnancy and embryogenesis of humans and other species...

 in the body. This is said to be caused by a decrease in progesterone without a subsequent decrease in estrogen. The theory is popular among natural health practitioners, but is generally not recognized by mainstream medicine

Medicine

Medicine is the science and art of healing. It encompasses a variety of health care practices evolved to maintain and restore health by the prevention and treatment of illness....

.

The theory was proposed by John R. Lee and Virginia Hopkins in their 1996 book, What Your Doctor May Not Tell You About Menopause: The Breakthrough Book on Natural Progesterone. This book criticized estrogen replacement therapy

Hormone replacement therapy (menopause)

Hormone replacement therapy is a system of medical treatment for surgically menopausal, perimenopausal and to a lesser extent postmenopausal women...

 and proposed the use of "natural progesterone" for menopausal women in order to alleviate a variety of complaints. It has also been promoted by Ronald Hoffman

Ronald Hoffman

Ronald Hoffman, M.D. is an American physician, author, and broadcaster in the United States who hosts Health Talk, a syndicated radio talk show. He is the founder and director of the Hoffman Center in New York City, and is a practitioner of holistic medicine...

, who hosts the "Health Talk" radio show. Lee's theories have been criticized for being inadequately supported through science, being primarily based on anecdotal evidence

Anecdotal evidence

The expression anecdotal evidence refers to evidence from anecdotes. Because of the small sample, there is a larger chance that it may be true but unreliable due to cherry-picked or otherwise unrepresentative of typical cases....

with no rigorous research to support them.