The declining estrogen levels associated with "the change" can interfere with metabolic processes leading to weight gain, US researchers said Monday, confirming what many women already knew.
The findings seem to support a link between the female sex hormone estrogen and regulation of obesity, especially the dangerous accumulation of abdominal fat linked to heart disease, diabetes and cancer, the study's authors said.
"The accumulation of abdominal fat puts both men and women at heightened risk of cardiovascular disease, diabetes and insulin resistance," said Deborah Clegg, assistant professor of psychiatry at the University of Cincinnati Academic Health Center in Ohio.
"Women are protected from these negative consequences as long as they carry their weight in their hips and saddlebags. But when they go through menopause and the body fat shifts to the abdomen, they have to start battling all of these medical complications," she added.
In experiments on rats, Clegg showed that when they cut off the estrogen supply to a part of the brain that is central to energy regulation, the rats quickly developed an impaired tolerance to glucose and a sizable weight gain, even when they took in the same amount of calories.
What's more, the excess weight went straight to their middle sections, creating an increase in visceral fat.
The findings suggest that estrogen receptors in the ventromedial nucleus, a region of the hypothalamus, plays an essential role in controlling energy balance, body fat distribution and normal body weight. The hypothalamus controls body temperature, hunger and thirst.
By identifying critical brain regions that determine where body fat is distributed, Clegg's findings may help scientists formulate "designer" hormone replacement therapies to better manage and manipulate estrogen levels.
"If we could target those critical regions and estrogen receptors associated with weight gain and energy expenditure, we could perhaps design therapies that help women sidestep many of the complications brought on by the onset of menopause," she said.
Clegg presented her study in Boston at the 234th national meeting of the American Chemical Society.