Why the body's appetite hormones fight to restore lost weight.
What the evidence says
- After diet-induced weight loss, appetite-regulating hormones change to encourage weight regain1
- One year after weight reduction, these hormonal changes persist — they do not revert to pre-weight-loss levels1
- Leptin drops after weight loss, reducing satiety signals — you feel less satisfied1
- Ghrelin (hunger hormone) rises after weight loss, increasing hunger drive1
- Subjective appetite ratings remain elevated one year post-weight-loss1
- Creates biological pressure to regain weight that persists for years1
- Leptin replacement during maintenance of reduced weight reversed two-thirds of the fall in TEE and activity energy expenditure — demonstrating leptin's causal role in post-weight-loss metabolic suppression2
- For each kilogram lost, appetite increases ~100 kcal/day above baseline while expenditure decreases only ~20-30 kcal/day — appetite increase is 2-3x greater than metabolic adaptation3
- At weight plateau (~6 months), appetite has risen 400-600 kcal/day while expenditure decreased less than 200 kcal/day — appetite, not metabolism, is the primary driver of plateaus and regain3
- Appetite regulation occurs in brain regions below conscious awareness, potentially causing portion sizes to drift upward without detection3