Fat and carbohydrate interact to potentiate food reward in healthy weight but not in overweight or obesity
Prior work suggests that actual, but not estimated, energy density drives the reinforcing value of food [1,2] and that energy from fat and carbohydrate can interact to potentiate reward [2]. Here we sought to replicate these findings in an American sample and to determine if the effects are influenced by body mass index (BMI). Thirty participants with healthy weight (HW; BMI 21.92 {+/-} 1.77; M {+/-} SD) and 30 participants with overweight/obesity (OW/OB; BMI 29.42 {+/-} 4.44) rated pictures of common American snacks in 120-kcal portions for liking, familiarity, frequency of consumption, expected satiety, healthiness, energy content, energy density, and price. Participants then completed an auction task where they bid for the opportunity to consume each food. Snacks contained either primarily carbohydrate, primarily fat, or roughly equal portions of fat and carbohydrate (combo). Replicating prior work, we found that participants with HW bid the most for combo foods in linear mixed model analyses. This effect was not observed among individuals with OW/OB. Additionally, in contrast with previous reports [1,2], our linear regression analyses revealed a negative relationship between the actual energy density of the snacks and bid amount that was mediated by food price. Our findings support altered macronutrient reinforcement in obesity and highlight potential influences of the food environment on the regulation of food reward.