Ever wonder why men and women gain weight in different areas of the body? Researchers say they are coming close to understanding the vital sex differences in men and women concerning fat storage. In fact, research indicates that fat is genetically different in men and women.

A recent medical study claims to uncover new truths about fat deposition in male and female mice that have important implications for humans. The study was sponsored by the Society for Women's Health Research (SWHR) and was released by members of its Isis Fund Network on Sex Differences and Metabolism.

"Given the difference in gene expression profiles, a female fat tissue won't behave anything like a male fat tissue, and vice versa," says Deborah Clegg, assistant professor of internal medicine at the University of Texas Southwestern Medical Center, in Dallas. "The notion that fat cells between males and females are alike is inconsistent with our findings."

Mice store their fat similar to humans in a sexually dimorphic pattern. Just like human males, male mice store their fat in the belly and midsection area while females store fat in their hips, thighs, and buttocks. Fat around your central organs—also known as central adiposity—is the type that's most dangerous for subsequent development of chronic diseases.

Clegg, the senior author of the study appearing in the International Journal of Obesity, was surprised by the findings.

"We found that out of about 40,000 mouse genes, only 138 are commonly found in both male and female fat cells," she says. "This was completely unexpected. We expected the exact opposite—that 138 would be different and the rest would be the same between the sexes."

The discovery could be helpful in determining the underlying causes of obesity-related diseases, researchers say. Since men are more likely to carry extra weight around their bellies, they are at higher risk for numerous obesity-related diseases including diabetes and heart disease. Women, on the other hand, usually are protected from these disorders until menopause, when their ovarian hormone levels drop and fat storage tends to shift from their buttocks to their waists.

SWHR, a nonprofit organization based in Washington D.C., touts itself as a leader in women's health research, particularly how sex differences impact health. The organization's mission is to improve the health of all women through advocacy, education, and research.