The Impact of Prescribed Exercise on Non-Exercise Activity during Short-Term Caloric Restriction
Caloric restriction (CR) has been shown to reduce total daily energy expenditure (EE), which attenuates further weight loss. It is unknown how the addition of exercise to CR impacts physical activity behavior outside of prescribed exercise, specifically non-exercise activity thermogenesis (NEAT) and time spent in moderate-to-vigorous (MVPA) and light-intensity physical activity (LPA). In a repeated-measures crossover design, active men (n=6, 25 ± 1.0 y) underwent four 4-day energetically-matched conditions of CR with and without low-to-moderate intensity aerobic exercise (CR+EX, CR-EX), during which energy availability was reduced to 15 kcal∙kg FFM-1∙day-1, and two energy-balanced control conditions (CON+EX, CON-EX). The duration and intensity of physical activity were assessed using the SenseWear Pro3 armband. Both CR conditions resulted in body mass loss (p<0.001). After deducting prescribed exercise, MVPA did not differ between conditions, but time spent in LPA was ~10 % greater in CR-EX than CR+EX (p=0.02). Physical activity (2.98 ± 0.12 vs. 2.72 ± 0.12 METs, p=0.02) and NEAT (295 ± 22 vs. 230 ± 37 kcal∙hr-1; p=0.04) during non-lying time was greater during CR+EX than CR-EX. The addition of exercise to CR reduced time spent being inactive and increased NEAT, indicating a further benefit of incorporating exercise into weight loss interventions.
weight loss, non-exercise activity, behavioral compensation, inactive time, MVPA