Rodent of the Week: Male fat is different from female fat

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Men often carry extra weight on their stomachs while women tend to accumulate fat on the butt, hips and thighs. A new mouse study suggests why: It seems that female fat tissue and male fat tissue behave very differently.

Researchers at UT Southwestern Medical Center in Dallas examined mouse genes (fat distribution in mice is similar to humans) and found only 138 genes that were common to both male and female fat cells. That means that fat on men is governed by a largely different gene expression profile than fat on women.

After menopause, women’s fat distribution often changes and women become more susceptible to belly fat. A woman’s risk of heart disease also rises. The discovery of distinct male and female fat genes might yield clues to understanding what happens after menopause, said the lead author of the study, Dr. Deborah Clegg.

The study also showed that male mice consuming a high-fat diet for 12 weeks gained more weight than female mice on the same diet. The male’s fat tissue also became more inflamed than the females’ fat. But when the female mice had their ovaries removed to induce menopause, their fat began looking much more like male fat.

‘However, estrogen replacement therapy in the mice reduced the inflammation and returned their fat distribution to that of mice with their ovaries intact,’ Clegg said in a news release.

The study raises the possibility that hormones produced by the ovaries determine where fat is deposited in women. Clegg’s future research will focus on whether a type of hormone replacement therapy can be developed for postmenopausal women to protect them from belly fat accumulation and heart disease.

The study was published this week in the International Journal of Obesity.

-- Shari Roan