Mixed
During caloric overfeeding, increasing dietary protein from 5% to 15-25% of energy significantly reduces total weight gain by increasing energy expenditure and preserving lean body mass, without altering the amount of body fat gained.
If you are in a caloric surplus, your body will store the excess energy as fat regardless of whether you eat high or low protein. However, eating a higher amount of protein (15-25% of calories) will cause your body to burn more energy and build more muscle, resulting in less *total* weight gain compared to a low-protein diet, even though the amount of fat gained is the same. To minimize total scale weight gain while overeating, prioritize protein.
Overeating produced significantly less weight gain in the low protein diet group (3.16 kg; 95% CI, 1.88-4.44 kg) compared with the normal protein diet group (6.05 kg; 95% CI, 4.84-7.26 kg) or the high protein diet group (6.51 kg; 95% CI, 5.23-7.79 kg)... Body fat increased similarly in all 3 protein diet groups... Resting energy expenditure... and body protein (lean body mass)... increased significantly with the normal and high protein diets.
Why this rating
Randomized controlled trial in a metabolic ward with rigorous measurement of energy expenditure and body composition.
Source
Effect of Dietary Protein Content on Weight Gain, Energy Expenditure, and Body Composition During Overeating
George A. Bray et al. · JAMA · 2012
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