Higher Protein Diets Don't Prevent Appetite Hormone Rebound After Weight Loss

Higher-protein, low-GI diet for weight maintenance did not attenuate post-weight-loss changes in ghrelin or PYY compared to moderate-protein diet, and appetite hormone changes did not predict weight regain over 3 years.

Sub-study of the PREVIEW RCT. 136 adults with pre-diabetes underwent 2-month weight loss (≥8% body weight), then randomized to two dietary patterns for 34 months. Fasting ghrelin, PYY, and appetite sensations measured at 0, 2, 6, 12, 24, and 36 months.

The idea that higher-protein diets could counter hormonal drivers of weight regain is popular but largely unproven. This well-designed long-term study provides important evidence that diet composition may not be sufficient to override the body's weight-regain physiology.

Weight regain after dieting remains one of the biggest challenges in obesity management. This study suggests that hormonal appetite regulation may be more resilient than previously thought — returning toward normal within months — and that weight regain likely involves other factors beyond ghrelin and PYY changes.

Sub-study of a larger trial with limited statistical power. Measured only total ghrelin and total PYY (not active forms). Self-reported dietary adherence. High attrition common in long-term diet studies.