The adaptive metabolic response to exercise-induced weight loss influences both energy expenditure and energy intake

BACKGROUND/OBJECTIVES: A decline in resting energy expenditure (SEE) beyond that predicted from changes in body composition has been noted following dietary-induced weight loss. However, it is unknown whether a compensatory downregulation in REE also accompanies exercise (EX)-induced weight loss, or whether this adaptive metabolic response influences energy intake (El). SUBJECTS/METHODS: Thirty overweight and obese women (body mass index (BMI) =30.6 +/- 3.6 kg/m(2)) completed 12 weeks of supervised aerobic EX. Body composition, metabolism, El and metabolic-related hormones were measured at baseline, week 6 and post intervention. The metabolic adaptation (MA), that is, difference between predicted and measured SEE was also calculated post intervention (MA(post)), with SEE predicted using a regression equation generated in an independent sample of 66 overweight and obese women (BMI =31.0 +/- 3.9 kg/m(2)). RESULTS: Although mean predicted and measured SEE did not differ post intervention, 43% of participants experienced a greater-than-expected decline in SEE ( 102.9 +/- 77.5 kcal per day). MA(post) was associated with the change in leptin (r= 0.47; P=0.04), and the change in resting fat (r= 0.52; P=0.01) and carbohydrate oxidation (r= 0.44;P= 0.02). Furthermore, MApost was also associated with the change in El following EX (r= 0.44; P=0.01). CONCLUSIONS: Marked variability existed in the adaptive metabolic response to EX. Importantly, those who experienced a downregulation in SEE also experienced an upregulation in El, indicating that the adaptive metabolic response to EX influences both physiological and behavioural components of energy balance.