The Effect of Experimentally Induced Cognitive Fatigue on Energy Intake Among Youth With and Without Recent Reported Dietary Restraint

Objective: Resource-based models of self-regulation posit that cognitive fatigue, or the depletion of cognitive resources, may be an impetus for self-regulatory difficulties, including overeating. Studies of adults indicate that cognitive fatigue may increase energy intake only among adults who report engaging in dietary restraint (DR). The current study examined if DR similarly moderates the effects of cognitive fatigue on energy intake in youth. Method: Using a randomized crossover design, participants completed a two-hour cognitive fatigue and a non-fatigue control (i.e., watched movies) condition, on separate days within a 31-day period. Energy intake (kcal) was evaluated using a ~10,000 kcal buffet-style meal presented after each condition with the instructions to “Please eat until you are no longer hungry.” DR was assessed via the Eating Disorder Examination. Results: Participants included 98 youth (13.0 ± 2.56 years; BMI%ile 60.06 ± 29.01; 46.9% Female; 46.9% non-Hispanic White, 20.4% non-Hispanic Black, 12.2% non-Hispanic Asian; 20.4% endorsed engaging in any DR within the prior 28 days). After adjusting for height, fat mass (%), lean mass (kg), sex, race/ethnicity, visit order, and days between visits, the interaction of DR and experimental condition was associated with energy intake, F(1, 88) = 8.60, p = 0.004, η²_p = 0.089. Youth with DR had greater intake following the fatigue (vs. control) condition, but intake did not differ by condition among youth without DR. Discussion: DR may weaken youth's efforts to regulate energy intake when cognitively fatigued. Studies utilizing more comprehensive measures of DR are needed to elucidate whether this association differs across DR phenotypes and in naturalistic environments. Trial Registration: This study was pre-registered (https://clinicaltrials.gov/ct2/show/NCT02390765).