Energy balance

Long-term caloric restriction (25% reduction for 24 months) induces metabolic adaptation (adaptive thermogenesis) in sleeping energy expenditure that exceeds predictions based on changes in body mass alone, with the effect persisting at 24 months when assessed using advanced MRI-derived organ and tissue mass models.

If you restrict calories by 25% for two years, your body will adapt by lowering its energy expenditure more than expected from weight loss alone. This 'metabolic adaptation' is real and persists, especially when looking at organ-level changes. To manage this, focus on preserving muscle mass through resistance training and protein intake, as the study shows lean tissue loss is part of the equation, though not the whole story of metabolic slowdown.