Obesity study finds new link

A recent study that connects high estrogen levels with weight loss could suggest a novel solution for the problem of obesity.

Researchers at the Yale School of Medicine have shown that estrogen may curb hunger, a finding which could lead to new methods of treating obesity — especially for those resistant to leptin, a common weight-control hormone. Scientists have known about leptin’s effects on fat storage and long-term body weight for a decade, but Yale researchers have now discovered that estrogen acts in a similar capacity. Their results were reported in the Dec. 31 issue of Nature Medicine.

School of Medicine professor Tamas Horvath, who led the study, said the connection between estrogen and body weight can be seen in the experience of the many women who add body fat upon entering menopause, when estrogen levels go down. Though body fat and weight levels are reliant upon many factors, including other hormones, genes and diet, scientists said their experiments showed that estrogen has a definitive individual effect.

“We used animals that were the same age and from the same genetic background, and we found a 100 percent correlation,” said professor Qian Gao, a co-author of the study. “When we decreased estrogen, the animals gained more fat, and when we increased estrogen, the animals became less fat.”

Leptin is the main weight-controlling hormone, and the body does not naturally utilize estrogen as a secondary method to control hunger, Gao said. Though the correlation between estrogen and appetite is clear, there are possible negative side effects, he said. Estrogen may be able to reduce weight, but it could also increase the tissue mass of breasts, ovaries or the uterus.

Horvath and his team are working to identify compounds, called selective estrogen receptor modulators (SERMs), that would maintain estrogen’s weight-controlling properties in the brain but would not produce unwanted side effects in other parts of the body, said Richard Hochberg, a Yale professor involved in the study. SERMs act as estrogen would in some tissues but not in others, he said.

“It all depends how they interact, which has to do with the way they affect estrogen receptors,” Hochberg said.

Though the study of estrogen and its effect on the brain and feeding behavior is in its early stages, Horvath said, his team is hopeful about the hormone’s possible role in treating obesity.

“Estrogen in obesity treatment potentially has a great future because there are no medications against obesity, which is becoming a bigger problem,” Horvath said. “Anything that would be a novel way of approaching this problem gives us hope that … we may possibly find a solution.”

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