Influence of a High-Fat Diet on Delay Discounting, Food Reinforcement, and Eating Behaviors in Sedentary and Endurance Trained Men

People make food choices based upon the motivation to consume foods that are reinforcing compared to alternatives that may be available.1 Delay discounting (DD) is a measure used to assess impulsivity, quantifying how people make decisions based on time to receive and amount of the choice presented. The food purchase task (FPT) assesses the demand for a food and how reinforcing this item is at various prices. Using a controlled feeding study design, 10 males (n=7 sedentary, n=10 endurance trained) consumed an iso-caloric, standard diet (55% carbohydrate, 30% fat, and 15% protein) for 10 days, followed by a high-fat diet (55% fat, 30% carbohydrate, 15% protein) for 5 days. DD, FPT, and Three Factor Eating Questionnaire (TFEQ) were assessed at three time points: baseline, after the standard diet/before high-fat diet, and after the high-fat diet. Discounting rates were significantly different at baseline between sedentary and endurance trained males, with the sedentary males having higher discounting rates (mean difference 1.43, p=.037). Discounting rates for the whole sample significantly decreased between baseline (time 1) and post-STD diet/before HFD (time 2), between time 2 and after the HFD (time 3), and between time 1 and time 3 (all indicated by p<0.05). No group differences were noted over time for demand elasticity, intensity, or TFEQ measures (all indicated by p<0.05). Results could be used to advance the understanding of factors that influence impulsive and unhealthy eating behaviors and inform the development of interventions that use reinforcers to positively influence eating behaviors.