This study investigated the contributions of tissue loss and metabolic adaptations to the reduction in resting metabolic rate (RMR) following weight loss. A secondary analysis of data from the CALERIE study (n=109) examined changes in RMR, body composition, and metabolic hormones over 12 months of calorie restriction. Results showed a 101 ± 12 kcal/d reduction in RMR with a 7.3 ± 0.2 kg weight loss. Approximately 60% of the RMR reduction was attributed to tissue loss, with adipose tissue loss, rather than skeletal muscle loss, being significantly associated with RMR reduction. The remaining 40% was attributed to metabolic adaptations, correlated with declines in leptin, triiodothyronine, and insulin. The findings suggest that both tissue loss and metabolic adaptations contribute significantly to RMR reduction after weight loss, highlighting the need for personalized strategies to address these factors for successful weight maintenance.

Alexandra Martin, Darius Fox, Chaise A. Murphy, Hande Hofmann, Karsten Koehler