Women are less able to suppress hunger when faced with their favourite foods
Women are less able to suppress their hunger than men when faced with their favourite foods, a discovery that may help explain the higher obesity rate for females, a new study suggests.
Gene-Jack Wang of Brookhaven National Laboratory and colleagues were trying to figure out why some people overeat and gain weight while others don't and their findings left them surprised at how the brains mechanisms for controlling food intake differed between the sexes.
The test performed brain scans on 13 women and 10 men, who had fasted overnight, to determine how their brains responded to the sight of their favourite foods.
"There is something going on in the female," Wang said, "the signal is so much different."
The day after their fast the participants underwent brain scans while being presented with their favourite foods. In addition, they used a technique called cognitive inhibition, which they had been taught, to suppress thoughts of hunger.
While both men and women said the inhibition technique decreased their hunger, the brain scans showed that men's brain activity actually decreased, while the part of women's brains that responds to food remained active.
"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," Wang said.
Nora Volkow, director of the National Institute on Drug Addiction and a co-author of the paper, said the gender difference was a surprise and could be a result of different nutritional needs for the sexes. She stressed that this idea is speculative though.
She said that as the traditional role of females is to provide nutrition to children the female brain could be wired to eat when food is available. The next stage in the study is to see if female hormones are reacting directly with those parts of the brain.
Eric Stice, an expert on eating disorders at the Oregon Research Institute, called the findings provocative.
"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," said Stice, who was not part of Wang's research team.
The study was funded by the National Institute on Drug Abuse, the National Institute on Alcohol Abuse and Alcoholism, and by the General Clinical Research Center of Stony Brook University.