Just Saying No Can Be Tougher for Women
Hormones and evolution may hinder efforts to stay slim
(HealthDay News) -- In news that will come as no surprise to most women, they have a harder time than men in turning down favorite foods.
Why this appears to be the case isn't clear, though researchers suspect that the need to sometimes eat for two might be the evolutionary driver behind a woman's desire for food.
"This gives us another piece to put into this puzzle," the study's author, Dr. Gene-Jack Wang, a senior scientist at Brookhaven National Laboratory and a psychiatry professor at Mount Sinai School of Medicine in New York City, told HealthDay. "Maybe evolution leads them to this because of their important mission to have a baby."
And, biology may be putting a double-whammy on women: They must eat less -- take in fewer calories -- than men to maintain the same weight. For example, a 150-pound man who participates in light activity (defined as about 4,000 steps walking a day) needs about 2,591 calories a day to maintain his body weight, according to the American Cancer Society. But a woman who weighs 150 pounds and participates in the same activity needs only 2,386 calories a day to maintain her weight.
Wang initiated the research to try to understand why people don't stop eating when they're full -- one of the biggest reasons that people are overweight. Though your body tells you that you've eaten enough by sending a signal to your brain from the gut, he explained, "if you go to the buffet, sometimes you just cannot stop."
Until recently, these missed signals weren't a big deal because people didn't have access to an overabundance of food. But in the past 30 to 40 years, Wang said, that's changed, and the body has not yet adapted to the near constant availability of sustenance.
Wang and his colleagues interviewed 13 women and 10 men about their favorite foods -- lasagna, pizza, brownies, ice cream and fried chicken. Then, after a 20-hour fast, the researchers placed favorite foods in front of the study participants. They were allowed to smell and even to taste the food, but they weren't allowed to eat it. The researchers then told the study volunteers to try to dampen their desire for the food.
While all of this was going on, the brain activity of the study participants was scanned, using positron emission tomography (PET) imaging.
Particular areas of the brain became more active as people tried to resist their favorite foods, the researchers found. The areas that appeared most active were areas that control emotions, such as motivation.
Although both the men and women said they felt less hungry, the women's brains were still active in the area that indicates hunger, suggesting that their brains still wanted the women to get the food.
Evolution and hormones could be the cause, said Wang. Women need to eat more when they're pregnant, and the brain might be urging that behavior.
Wang said that the findings, published in the Proceedings of the National Academy of Sciences, could help scientists understand why high-calorie food is so irresistible to some people. "Some people cannot inhibit themselves, and we need to help those people," he added.
On the Web
To learn more about healthy eating, visit the U.S. Centers for Disease Control and Prevention. http://www.cdc.gov/healthyweight/healthy_eating/index.html
SOURCES: HealthDay News; Gene-Jack Wang, M.D., senior scientist, Brookhaven National Laboratory, Upton, N.Y., and professor, psychiatry, Mount Sinai School of Medicine, New York City; Jan. 19, 2008, Proceedings of the National Academy of Sciences; American Cancer Society (www.cancer.org)
Author: Serena Gordon
Publication Date: Jan. 31, 2010
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