Obesity May Affect Women Differently Than Men

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Women may become overweight for different reasons than men, according to a recent study published in the journal Cell Biology. Obese women appear to have a specific, food-related "learning deficit" that was not observed in obese men or normal-weight individuals, say researchers, and it may affect why they gain so much weight in the first place.  

To determine how their study volunteers might react toward certain environmental cues, researchers presented the men and women with different colored squares followed by pictures of rewards (either food or money). Eventually, the participants were asked to predict the likelihood of being shown a reward after one color or another based on the patterns they'd already observed. 

Only obese women struggled to accurately predict when a food picture would appear—but they had no problem predicting pictures of money. This suggests a type of very specific learning impairment, the study authors say, that only relates to food—and, for some reason, only affects this specific group. 

"I must admit that we did not expect a gender difference," says co-author Ifat Levy, Ph.D., a neuroscientist at Yale University. One possibility, she says, is that obese people may face additional "cognitive loads" when it comes to food—in other words, they have a harder time blocking out food-related distractions. "Women are generally more concerned about being obese or their appearance, and therefore this load may be heavier for women." 

Other reasons, the researchers speculate, may have to do with hormones, or with sex-specific differences in the prefrontal cortex, an area of the brain involved in learning and reward-seeking behavior. 

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More research will be needed to determine whether such a learning deficit actually causes obesity or whether obesity triggers the learning deficit. In any case, the finding may shed some light on why some people eat more than others, says Levy. "It could be that obese individuals—or at least obese women—fail to flexibly adjust their valuation of food. For example, when we are hungry, food is perceived as highly rewarding," she explains. "But when we are full, the food is much less rewarding and can even be aversive. It is possible that some obese individuals fail to recognize the change in their internal environment, and thus keep regarding the food as highly rewarding even when it should not be." 

Levy hopes that her study can serve as a basis for new gender-specific weight-loss interventions that focus not on food itself, but on internal and external cues and how they affect people's reactions to food. "Perhaps by modifying the flawed associations between cues and food, it would be possible to change eating patterns," she says. 

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