Your body defends a particular weight range — this is your set point. Lose weight and it fights back: metabolic rate drops beyond what the smaller body explains, ghrelin rises, and muscle does about 20% more work per calorie. The Biggest Loser contestants were still running a 499-calorie-a-day adaptation six years on, and in those who regained the weight it had worsened rather than eased. Across 29 long-term studies, more than half of lost weight returned within two years and more than 80% by five — a measure of how much weight comes back, not of how many people fail. What sets the set point is genuinely unsettled; this companion takes the carbohydrate-insulin model seriously while marking clearly where its physiology ends and its contested causal claim begins.
Also: why the defense is lopsided, and what the fasting evidence does and doesn’t show. (9 min read)