Ever wonder why men seem to be able to drop the pounds just by cutting out the white bread, while women can limit themselves to carrot sticks and hardboiled eggs—and still be stung by the scale?
The odds a woman is trying to lose weight are 1 in 2.29, and a man, 1 in 3.47. When it comes to the size of the struggle, maybe men really are from Mars and women from Venus. Different planetary origins could explain the big differences between the sexes, at least when it comes to our appetites—and our fat cells. Because, as it turns out, all fat is not equal. And that can make a big difference in how men and women lose weight.
Men tend to store fat in their bellies. Premenopausal women tend to store it in their hips. That’s been known, and associated with differing health risks, for years. Belly fat is linked to heart disease and diabetes, for example, and men do indeed have these conditions in greater percentages. The odds a female has been diagnosed with diabetes are 1 in 18.52, while for a male they’re 1 in 17.24. For heart disease the differential is far more dramatic: the odds a woman 20 or older has coronary heart disease are 1 in 16.39, while for men they’re 1 in 11.24.
But body location isn’t the only thing distinguishing male and female fat cells, according to new research on mice.
Mice, it turns out, distribute their body fat similarly to humans: males around their bellies, females more in the hips. Reporting in the International Journal of Obesity, a team led by Deborah Clegg at UT Southwestern Medical Center found that only a tiny minority of the animals’ genes, 138 out of about 40,000, are the same in male and female fat cells. All the other genes express themselves differently. So it seems only natural that male and female fat tissue will behave differently. And sure enough, Dr. Clegg found that a high-fat diet caused more inflammation in the males’ fat cells, especially around their bellies.
Female mice with their ovaries removed to simulate menopause reacted more like the male mice—and hormone replacement reversed those effects.
The research may ultimately contribute to explaining why men and women often get different results when they try to lose weight. Dr. Clegg’s work adds to previous findings about the complex forces at work on our metabolisms, and how some of them differ by gender:
- Men have more muscle mass and less fat to begin with, so they burn more calories both at rest and during physical activity. This tends to make it easier for them to lose weight.
- In an earlier experiment on rats, Dr. Clegg found that injecting the appetite-related hormone leptin caused females, but not males, to eat less and lose weight. Insulin had a similar effect on males, but not females.
- The brain, too, plays a big role in appetite control. A 2008 brain-scan study found that men could suppress their conscious yen for food after their appetites had been stimulated, but women couldn’t.
- Recently, adults were found to possess some of the energy-burning “brown fat” once thought to exist only in babies. Medically manipulating the functioning of this tissue might lead to treatments for (or even prevention of) obesity.
“It’s a new metabolic world,” wrote Stockholm University’s Jan Nedergaard in an April issue of Cell Metabolism. And that’s just Earth—never mind Mars and Venus.
Originally published on Book of Odds
