Report Habitual daily intake of a sweet and fatty snack modulates reward processing in humans

Western diets rich in fat and sugar promote excess calorie intake and weight gain; however, the underlying mechanisms are unclear. Despite a well-documented association between obesity and altered brain dopamine function, it remains elusive whether these alterations are (1) pre-existing, increasing the individual susceptibility to weight gain, (2) secondary to obesity, or (3) directly attributable to repeated exposure to western diet. To close this gap, we performed a randomized, controlled study (NCT05574660) with normal-weight participants exposed to a high-fat/high-sugar snack or a low-fat/low-sugar snack for 8 weeks in addition to their regular diet. The high-fat/high-sugar intervention decreased the preference for low-fat food while increasing brain response to food and associative learning independent of food cues or reward. These alterations were independent of changes in body weight and metabolic parameters, indicating a direct effect of high-fat, high-sugar foods on neurobehavioral adaptations that may increase the risk for overeating and weight gain.

Automated summary

Western diets rich in fat and sugar can lead to excessive calorie intake and weight gain. However, the exact mechanisms behind these effects are not yet fully understood. To address this, a controlled study was conducted, exposing normal-weight participants to either a high-fat/high-sugar or a low-fat/low-sugar snack for 8 weeks in addition to their regular diet. The high-fat/high-sugar intervention resulted in a decrease in preference for low-fat food, increased brain response to food, and enhanced associative learning, independent of food cues or reward. These neurobehavioral adaptations, unrelated to changes in body weight or metabolic parameters, suggest a direct effect of high-fat, high-sugar foods on the risk of overeating and weight gain.