Stress overrides the brain's natural response to satiety, causing the pleasure to be derived from food to decrease. Stress also favors an increase in signals seeking "rewards," which translates into a hedonistic race toward eating more and more appetizing foods.
The vicious cycle is orchestrated in the brain by the neuropeptide NPY. When the researchers blocked NPY in the lateral habenula cells of stressed mice receiving a high-fat diet, the animals consumed less food and weight gain was slowed.