In young overweight men undergoing a 40% energy deficit and six days per week of combined resistance and high-intensity interval training, protein intakes of 1.2 g/kg/day and 2.4 g/kg/day produce similar improvements in strength, aerobic capacity, and anaerobic power.

When someone eats a lot of protein while losing weight and doing intense exercise, their muscles build more tissue because the body uses the extra amino acids to make new muscle proteins. But even though they get more muscle, their strength, endurance, and power don't improve any more than if they ate less protein, because the nervous system and muscle fibers are already being fully activated by the training itself.