Previous research has found that, compared to lean individuals, overweight or obese folks exhibit structural differences in regions of the brain linked to reward-processing and hunger regulation. Now, German neuroscientists looking at gender-differences in the brain structures of overweight men and women have uncovered a surprising result: Obese women show additional differences in the brain regions linked to impulse-control compared to woman with normal-range BMIs.
The new research, conducted at the Max Planck Institute for Human Cognitive and Brain Sciences, had 122 normal and overweight men and women between ages 18-45 participate in a game of luck called the Iowa Gambling Task. “In principle, this task mirrors the everyday trade-off between immediate reward from overeating and the negative long-term consequences this will have on one’s body,” said Annette Horstmann, principle investigator of the study.
Men in the study continually chose the option that promised higher short-term success but led to long-term losses, regardless of their weight. Obese women (determined as those with a BMI of 30 or higher) did the same; only the lean women“took the possible long-term consequences of their actions into account,” researchers note.
Overall, obese woman chose the short-term success option more than twice as many times as lean women.
After the game, all participants were given MRI scans.
In general, participants who were overweight had a greater density of grey matter in areas associated with reward processing. Likewise, the hypothalamus, a brain region known to be connected with the control of hunger and satiety, was much larger in overweight men and women. In contrast, areas associated with the cognitive control of goal-directed behaviour were significantly different between lean women and women who were overweight.
“The lack of impulse control which accompanies this is a further indication that obesity in otherwise healthy individuals should be classified as an addictive behaviour,” Horstmann said.
The same brain changes found in the obese women have also been found in previous studies examining women with bulimia. According to Horstmann’s study, which was published in the journal Frontiers in Human Neuroscience, this suggests that the brain differences are not directly connected with being overweight but with eating behavior itself.