Gaby
A team at the University of Edinburgh found that young men on a low-calorie diet shed fat twice as fast as young women — but that gap vanishes after about age 45.
The team attributes the difference to the hormone estrogen. Estrogen probably slows calorie burning in women of childbearing age because fat reserves support pregnancy.
By contrast, women approaching or past menopause lose weight more easily on low-calorie diets — good news for older women, the Daily Mail reports.
What the Researchers Discovered
The study suggests that women around age 45 lose more fat on a low-calorie diet than younger women.
Women in this age group can lose about 10 percent of their fat reserves by cutting calories over the course of a month. That is more than younger women typically achieve.
The research team recruited 42 volunteers of both genders, aged 21 to 61. All participants were overweight or obese and responded to a newspaper advertisement about a weight-loss study.
Over four weeks, participants ate three meals a day while reducing their calorie intake by an average of 30 percent.
Men consumed an average of 1,600 calories per day, while women consumed about 1,300.
Overall, men lost more fat than women, and young men lost twice as much fat as young women.
Men under 45 lost over 16 percent of their fat, while women in the same age group lost about 8 percent.
For participants aged 45 and older, however, the fat loss results were identical.
Both women and men lost an average of 10 percent of their fat on the low-calorie diet.
The same pattern appeared in an experiment with 96 mice. Under a low-calorie diet, young female mice burned fat more slowly than male mice.
The researchers concluded that fat tissue plays a role in fertility and reproduction.
That suggests women lose fat more easily through dieting after their reproductive years.
Dr. William Koutourn, the lead researcher, says these results are encouraging for women who struggled with excess weight when they were younger.
He says the findings give those women more reason not to give up.
Koutourn believes low-calorie diets have many health benefits and can help people age “correctly.”
Previous studies showed sex differences in how effective low-calorie diets are, but Koutourn says this new research is the first to show those differences largely disappear among older dieters.
The team plans further research to understand why men find it harder to burn belly fat as they age. They say lifestyle factors such as increased abdominal fat — sometimes called “beer bellies” — might play a role.
The study appears in the journal eLife.
