A new study in mice suggests that declining estrogen levels lower the taste buds' sensitivity to fats, which may drive a heightened appetite for fatty foods-;and weight gain-;after menopause. The study is published ahead of print in the American Journal of Physiology-Endocrinology and Metabolism. It was chosen as an APSselect article for March.

Previous research has shown that the hormone estrogen plays a role in appetite, food intake and body weight. However, there has been little study of sex differences within the taste system-;which includes cells in the taste buds that respond to different flavors (salt, sour, sweet, bitter, umami and fat) and activate hormone signaling throughout the body. "The taste system plays an important role in nutrient recognition and therefore shaping the diet," researchers of a new study wrote.

The researchers explored how estrogen activates fat taste signaling in male and female (pre- and postmenopausal) mice through a "bottle test" in which the animals were free to choose either plain water or water mixed with linoleic acid, a form of fatty acid. The research team also analyzed gene expression and signaling response in taste cells treated with estrogen.

The premenopausal female mice tended to drink less of the fatty acid-laced drink than water. This finding corresponded with the cell experiments that showed a greater response to fatty acids than in the males and postmenopausal females. The male and postmenopausal female mice-;both having lower circulating estrogen levels than the premenopausal females-;showed an increased preference for the fat-laden beverage over water.

In other words, "after loss of estrogen signaling, females [are] … less responsive to the chemical cues in dietary fats … leading them to eat more and put on more weight than when premenopausal," explained Timothy A. Gilbertson, PhD, of the University of Central Florida and corresponding author of the study.

These results in a mouse model could, in part, translate into why women have a harder time losing weight after menopause, Gilbertson said.