Introduction: Metabolic adaptation is a disproportionate reduction in resting metabolic rate (RMR)
during caloric restriction.
Methods: Data from the Lifestyle Intervention (LION) study (NCT04023942) were analyzed. RMR
was measured by indirect calorimetry at baseline (V1), after an 8-week formula-based
weight loss intervention (V2), after a 12-month weight maintenance intervention (V3),
and after 12-month follow-up (V4). Metabolic adaptation was calculated by 1) estimating
RMR by using an equation based on age, sex, fat mass, and fat-free mass, and 2) subtracting
RMRestimated from RMRmeasured. Regression analysis examined the association between weight loss and change in metabolic
adaptation from V1 to V2, adjusting for baseline variables.
Results: Data from 234 participants (age 46±11 years, BMI 34.3±2.8 kg/m2, 69% women) were included. Participants lost 11.7±3.5 kg (V1–V2), gained 2.0±7.7
kg (V2–V3), and gained 4.0±6.0 kg (V3–V4). Metabolic adaptation was 0.0±130.0 kcal/day
at V1, -70.9±109.9 kcal/day at V2, -1.2±130.0 kcal/day at V3, and 12.4±144.3 kcal/day
at V4. Change in metabolic adaptation was associated with weight loss from V1 to V2
(β=.005, p=.003).
Conclusion: Caloric restriction induced metabolic adaptation, which was associated with the
amount of weight lost.
