Men and women process, store fat differently, study suggests

Men and pre-menopausal women may process fat differently, leaving men at a greater risk for excess fat-related illnesses such as heart disease and obesity, a new study suggests.

“It had been really well reported that brain inflammation in males is associated with or causes metabolic syndrome [and] cardiovascular events,” study author Deborah Clegg, associate professor of diabetes and obesity research institute at Cedars-Sinai Medical Center in Los Angeles, Calif., told “We were interested in the question, do the females have the same changes in metabolism that the males have following consumption of the same diet?”

For the study, published Thursday in the journal Cell Reports, researchers fed male and female mice a diet high in carbohydrates, fat and sugar. Their diet was similar to eating a Big Mac and drinking a large soda every day. Forty-two of the mice’s calories came from fat. The typical American consumes between 38 and 48 percent of his or her calories from fat.

Researchers waited until the mice gained the same amount of weight because males usually are larger than females. When they did, the male mice developed type 2 diabetes and had enlarged hearts, which is associated with cardiovascular disease, while the females developed neither condition.

“Then we looked at the tissues of the animals,” Clegg said. “We found the brains of the males had elevations in markers of inflammation, and the females did not.”

When researchers removed the ovaries of the female mice to mimic menopause, they saw that the female mice’s fatty-acid tissue looked like the males’.

The dramatic compositional differences between the male and pre-menopausal female mice’s fatty acid tissue was the most surprising finding, Clegg said.

“The male brain tissue mirrored the types of fats that were in the diet. So basically, you’ve always heard you are what you eat. And that was true for the males,” Clegg said.

From Clegg’s previous research in 2011, she discovered that female fat tissues are like spandex. They can store extra fat, while males’ fat tissue can’t.

Study author Biff Palmer, an internal medicine professor at the University of Texas Southwestern Medical Center, said these findings align with what experts know about females and males biologically.

“The whole idea is that women tend to always accumulate fat in the hips and the thighs. We know biologically that site of storage has a lot of expandability,” Palmer told “In men, we accumulate more of our fat in the belly. Those fat cells have less expandability. The excess fat has to go somewhere— in this animal data we find that it goes to the brain.”

Evolutionary science shows that women tend to store more fat in their thigh and hip areas to prepare their bodies for pregnancy, while men tend to deposit fat in their pancreas, heart and, as the study suggests, in their brain.

“It goes back to the whole idea that women have this expandable depot, and men don’t,” Palmer said. “We’re [men] challenged with high-fat diets.”

If these findings hold true in clinical studies, they could impact how nutritionists offer dietary advice, said study author Aaron Frank, a registered dietician with a master’s degree in clinical nutrition from the University of Texas Southwestern.

“Understanding how sex influences how people handle these different diets could be very, very important,” Frank told “If I’m counseling a man, and we know— through some hypothetical test or screening that we’ve developed— that his brain or metabolism responds to these high-fat diets in a particular way, then we can really drill down and be specific and tailor his dietary intervention to avoid these particular things.”

Clegg said researchers will conduct clinical studies on male and female fatty acid tissues in cadavers, via brain biopsies, or by using imaging techniques.

“It has important implications in humans if it’s true,” Clegg said. “Maybe females occasionally don’t have to be concerned— that would be one take-home message. Eventually we need to individualize our medical approach. Right now, it is one-size-fits-all.”