The effects of high protein intakes during energy restriction on body composition, energy metabolism and physical performance in recreational athletes.

backgroundAthletes employ weight loss practices to lower body fat and maintain fat-free mass (FFM). High protein diets have been shown to produce greater fat loss and retention of lean mass during periods of energy restriction (ER) in sedentary individuals with obesity, but less is known about the effects of high protein diets in trained individuals during ER. Although current recommendations for protein intake in active individuals are 1.2-1.7 g/kg, it is unclear whether higher intakes are necessary to maximize FFM retention and maximize physical performance in athletes undergoing periods of ER.

objectiveDetermine whether high protein intakes could maximize FFM retention and physical performance in trained individuals after a period of ER.

methodsTwenty-one college aged athletes underwent a 6-week 25% ER + 3-day full body resistance training. Participants were randomly assigned to a low (~1.2 g/kg), moderate (~1.6 g/kg) or high (~2.2 g/kg) protein intake. Baseline and post-intervention outcomes: Dual X-ray absorptiometry, isotopic water dilution, indirect calorimetry, dietary records and strength based physical testing.

resultsSignificant reductions in body mass (p = 0.047) and fat mass (p = 0.04) with simultaneous increases in FFM (p = 0.037) were noted for all groups, with no protein intake effect. Significant increases in physical performance outcomes (5RM strength) were noted for most measures (p < 0.05).

conclusionCurrent protein intake recommendations of 1.2-1.7 g/kg appear sufficient for most athletes even during periods of ER to maintain FFM and physical performance.