Individuals whose brains don’t produce pleasure while eating will overeat in order to obtain it, generating changes that make them overindulge even more and, consequently, boost their risk of obesity, a new brain study finds.

Researchers at the Oregon Research Institute, University of Texas, Yale University and the John B. Pierce Laboratory also disclosed that individuals who have Taq1A1, a gene variation, are more prone to gain weight.

Lead author Eric Stice, a senior scientist at the Oregon Research Institute in Portland and colleagues recruited 43 women and 33 adolescent girls to find how much activity was in their brains' pleasure centers whilst serving the food.

Every single female participant was also tested for Taq1A1 allele, which is associated to a smaller quantity of dopamine receptors, a class of main receptors in the central nervous system. The amount of released dopamine receptors varies on the level of enjoyment the food generates. The participants were offered either a chocolate milk shake or a tasteless solution and after that, researchers performed MRI brain scans on them.

Based on the findings, which appeared in the Oct. 17 issue of the journal Science, researchers concluded that overweight or obese people don’t get more satisfaction from food than slim people do. It is the reduced level of pleasure they get from eating that makes them overindulge. And while trying to compensate for the reward deficit, they opt for more high-calorie food.

Additionally, the brain study’s results showed that women with low dopamine receptors were more likely to overeat than those with higher levels of these receptors, hoping to get similar satisfaction while eating. Thus, people with the Taq1A1 allele are more predisposed to obesity. “Obese people may have fewer dopamine receptors, so they overeat to compensate for this reward deficit,” Dr. Stice stated.