Energetic adaptations in response to moderate calorie restriction-induced weight loss in normal-weight adults.

Despite a considerable prevalence of normal-weight individuals engaged in dieting practices, energetic adaptations in response to weight loss are poorly studied in this population. This study aimed to examine the changes in energy expenditure and substrate oxidation rates during resting and exercise conditions, as well as the hormonal and metabolic profiles, after a diet-induced weight loss. The participants completed 3 identical experimental visits: baseline (T0, n = 35), 3% weight loss (T1, n = 32), 6% weight loss (T2, n = 18). During each visit, blood sample was performed at rest and indirect calorimetry measurements were performed in resting state and during walking exercise. While there was no change in resting energy expenditure, exercise energy expenditure decreased at T1 and T2 (p < 0.001). After weight loss, absolute carbohydrate oxidation rate was reduced at rest (p = 0.04) and during exercise (p < 0.001). The total cholesterol, triglyceride and leptin concentrations were reduced at T2 compared to T0 (p = 0.04, p = 0.008 and p = 0.02, respectively). This study highlighted changes in substrate use during weight loss, and the reduced energy expenditure during walking exercise observed during weight loss may promote weight (re)gain in normal-weight individuals.