Children with overweight, relative to lean, will work harder for a food reinforcer and consume more energy. Recent evidence from rodent models suggests that exposure to high energy dense foods has sex-dependent effects on motivation for food reinforcers. Sex differences may be due to differentiation in eating behaviors but this has yet to be explored.
Here we assessed lean (N=57, 43% female), overweight (N=16, 65% female), and obese (N=23, 48% female) adolescents ages 13-18 using a self-report questionnaire in which participants estimated the amount of work s/he would be willing to exert to obtain a food reinforcer over a non-food reward (activity). Participants stated their favorite food and activity, which represented the reinforcers, prior to the task to maximize personal relevance of outcomes. Sixty-four participants selected high-energy dense (HED) and 19 participants selected low-energy dense (LED) foods as their favorite. The amount of work required to earn the food reinforcer in this task increased exponentially whereas the amount of work required for the non-food reinforcer remained constant.
Overall, lean adolescents reported food as being more reinforcing compared with adolescents with overweight and obesity as measured by the number of estimated button presses for food compared with presses for the activity. Conversely, adolescents with overweight and obesity reported more motivation for the activity than the food reinforcer. Females with obesity responded significantly higher to the food reinforcer relative to males with obesity who responded significantly higher to the activity reinforcer. Lean and overweight males and females found food similarly reinforcing. There were no differences in responding between participants who selected HED or LED foods.
These data suggest that exposure to high energy dense foods may differentially affect motivation for food reinforcers in a sex-specific manner.