April health news: Why some women can't control their appetites

Can you control your hunger? If you're female, probably not, suggests a recent study.

According to researchers, when test participants were faced with their favourite foods, brain scans revealed that men were able to suppress their appetites and women could not. The findings may help to explain gender differences in obesity and binge eating.

"The big picture of our approach was to try to understand why we have so many obese people in our society," explains Gene-Jack Wang of Brookhaven National Laboratory in Upton, NY, and lead author of the study. "Overeating is linked to the dopamine system, which is related to our motivation, our habituation and especially our rewards. But we did not expect gender differences [to influence dopamine levels]."

Eliminating food from the brain
To test the brain's response to food and hunger, Wang and his team performed brain scans on 10 male and 13 female volunteers. Participants filled out a questionnaire ranking their favourite foods from one to 10 and then were asked to fast for 20 hours.

The next day, the volunteers were presented with their most preferred foods. "We showed the foods to them, we had them smell them, we had them talk about them and we let them taste them – but they weren't allowed to swallow," says Wang. "By giving them this kind of stimulation, we observed the release of dopamine." Meaning, the areas of the brain associated with emotion, conditioning and motivation lit up during the scan.

On another test day, the volunteers were asked to suppress their hunger when presented with the same foods. This time, while both genders said they felt less hungry, but the women's scans continued to light up while the men's brain activity in the food-related areas decreased.

Crossing the gender divide
Although the researchers can't pinpoint why the gender difference occurred, some theories have been tossed around. Wang says it could be a hormonal difference and it could be evolutionary.

"Women had the important mission to care for themselves and their babies, so they needed to eat more to respond to their environmental changes, our ancestors needed to eat more to not starve before they could find their next meal. Right now we don't have that problem, so overeating has become our disadvantage," he explains. "The study has opened up a Pandora's box. This is something we need to investigate further."

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