This study examined the effect of acute exercise on food motivation, energy intake, and total physical activity in normal-weight and obese women. Participants of both groups were matched (except for Body Mass Index) and conditions (exercise vs. non-exercise) were randomized and counter-balanced. Eighteen normal-weight and 17 obese women completed an exercise and non-exercise day, each performed on the same day of the week. Exercise was performed on a motor-driven treadmill at 3.8 mph and 0% grade for 45 continuous minutes. To test for food motivation, participants were shown a continuous stream of pictures of food and flowers (control) while neural activity was monitored. Data were analyzed using a 2-group x 2-exercise condition x 2-picture type repeated measures analysis of covariance on event-related potential (ERP) amplitude and latency. Dietary records were analyzed using the Food Processor SQL nutrition software. Physical activity was monitored using a GT1M accelerometer. For both groups under both conditions, ERP amplitude was higher and latency was lower for food pictures compared to flower pictures. When normal-weight and obese women were combined, there was a significant condition*picture type interaction for late positive potential (P=0.04) with participants showing less neurological response to food pictures following a 45-minute exercise bout. Exercise did not alter energy intake. However, the exercise condition resulted in significantly more total physical activity, moderate intensity, vigorous intensity, moderate-to-vigorous (MVPA) intensity activity, and less sedentary time than the non-exercise condition. There was a significant group*condition interaction for MVPA (P=0.043) with obese women showing less MVPA than the normal-weight group. The sample of women studied did not show neurological differences in response to pictures of food based upon BMI. However, exercise decreased neurological responses to food, which may indicate lower food motivation. A supervised and planned exercise bout dramatically increased total physical activity in normal-weight and obese women compared to a day without planned exercise. There may be some negative compensation for MVPA in obese women following a 45-minute exercise bout compared to normal-weight women.



College and Department

Life Sciences; Exercise Sciences



Date Submitted


Document Type





energy intake, food motivation, event-related potentials