Effect of exercising while fasting on eating behaviors and food intake

BACKGROUND Alternate day fasting combined with exercise is effective for weight loss. OBJECTIVE The aim of this study was to examine the behavioral adaptations that occur when ADF is combined with exercise, and to determine how these changes affect weight loss. DESIGN Obese subjects (n = 64) were randomized to 1 of 4 groups: 1) combination (ADF + endurance exercise), 2) ADF, 3) exercise, or 4) control, for 12 weeks. RESULTS Body weight decreased (P < 0.05) in the combination group (6 ± 4 kg), ADF (3 ± 1 kg), exercise group (1 ± 0 kg), with no change in the control group (0 ± 0 kg). When given the choice, subjects chose to exercise the same amount (P = 0.790) on the fast days (48 ± 2%) as feed days (52 ± 2%). Percent of exercise sessions performed on fast day mornings (20 ± 6%) did not differ (P = 0.453) from fast day afternoons (28 ± 5%). Likeliness to cheat on the fast day was not higher if the subject exercised in the afternoon (17 ± 7%) versus the morning (10 ± 5%). Hunger decreased (P < 0.05) while satisfaction and fullness increased (P < 0.05) post-treatment in the ADF group only. Restrained eating increased (P < 0.05) and uncontrolled eating decreased (P < 0.05) in the combination and ADF groups. CONCLUSION These findings suggest that endurance exercise is an excellent adjunct therapy to ADF, as it leads to positive behavioral changes that may contribute to long-term steady weight loss.