Metabolic adaptation
The drop in resting metabolic rate after weight loss, beyond what mass loss alone predicts.
Metabolic adaptation (sometimes called adaptive thermogenesis) is the tendency for resting metabolic rate to fall more than body-size changes alone would predict after weight loss, so the body burns fewer calories than expected. GLP-1 medications cut appetite but do not prevent this slowdown. After stopping, the suppression persists even as appetite surges. Importantly, in isolation metabolic adaptation correlates poorly with actual regain once confounders are controlled, so it should not be overstated; hormonal and behavioral factors dominate. Preserving muscle through protein and strength training helps protect metabolic rate.