LEVELS – A Whole New Level #290 - Why Weight Loss Is So Hard to Maintain—Metabolic Adaptation Explained | Dr. Eric Ravussin + Mike Haney
Jan 15, 2026
Dr. Eric Ravussin, a leading expert in human metabolism and obesity, shares key insights from his extensive research, including landmark studies like CALERIE and the Biggest Loser. He explains why BMI is an inadequate obesity measure and delves into the dynamics of energy expenditure. The discussion covers metabolic adaptation and its persistence post-weight loss, the implications of GLP-1 drugs on metabolism, and why unwavering willpower isn't the solution. Ravussin also debunks myths around obesity, emphasizing genetic and environmental influences.
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Body Actively Defends Weight
- The body defends its weight through physiological mechanisms rather than simple willpower.
- Metabolic adaptation and appetite regulation create a biological pull back toward prior weight.
Energy Expenditure Is Multi-Part
- Daily energy expenditure splits into sleeping, resting, thermic effect, spontaneous activity, and voluntary activity.
- Each component responds differently to weight change and influences total calorie burn.
Metabolic Adaptation Explained
- Metabolic adaptation means energy expenditure changes more than predicted by body-size changes.
- Weight loss makes the body more energy efficient, and weight gain does the opposite.