January 20, 2009

Women Less Able To Control Appetite Than Men

New research may be able to explain why men are more capable of watching what they eat than women.

Women's brains are at fault, researchers said in their report published in Proceedings of the National Academy of Sciences.

"There is something going on in the female," lead researcher Gene-Jack Wang, of Brookhaven National Laboratory, told the Associated Press. "The signal is so much different."

He and his colleagues compared the results of positron emission tomography (PET) brain scans from 13 women and 10 men. All participants had fasted the previous night. A form of glucose was tagged with a radioactive tracer molecule and injected into the blood stream while subjects lie in the PET scanner.

Researchers hoped to see how both sexes reacted when faced with their favorite foods, including pizza, chocolate cake and hamburgers.

"Even though the women said they were less hungry when trying to inhibit their response to the food, their brains were still firing away in the regions that control the drive to eat," said Wang.

About 35 percent of American women are obese, compared to about 33 percent of men, according to the US Centers for Disease Control and Prevention in 2006.

"The decreased inhibitory control in women could underlie their lower success in losing weight while dieting when compared with men," said Wang.

"Lower cognitive control of brain responses to food stimulation in women compared to men may contribute to gender differences in the prevalence rates of obesity and other eating disorders."

"It's a very interesting observation but we don't really know why men are better than women at inhibiting their appetite."

"I think it is very possible that the differences in hunger suppression may contribute to gender differences in eating disorders and that they are likely linked to gender differences in estrogen and related hormones," Eric Stice, an expert on eating disorders who was not involved with Wang's study, told AP.

Nora Volkow, director of the National Institute on Drug Addiction, co-authored the report. She said the difference could be linked to different nutritional needs. The next step is to see if female hormones are reacting directly with those specific parts of the brain, she said.

"A woman's menstrual cycle can be an important factor in responsiveness to reward and in successful quit attempts for smoking," said Volkow. "Its role in inhibiting food-related brain activation will be important to address in future studies."

"Our findings may help us understand the neurobiological mechanisms underlying the ability to control food intake, and suggest new pharmacological methods or other interventions to help people regulate eating behavior and maintain a healthy weight," said Wang.


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