The impact of high protein intake on body composition in active females during a hypoenergetic diet

Abstract

Purpose: To examine the impact of high protein intake on whole body composition changes in total body mass, lean body mass and fat mass as well as exercise performance following a short-term hypoenergetic diet in active females. Methods: In a parallel design, 18 healthy active females were prescribed 100% of their habitual energy intake for one week. Participants were then assigned to a hypoenergetic diet (60% of habitual energy intake) consisting of either a normal protein diet (CON, 15% protein total energy intake, n = 9) or a high protein diet (HP, 35% protein total energy intake, n = 9) for a 2-week period. Macronutrient composition during the hypoenergetic diet was set at 15% PRO, 50% CHO, 35% FAT for CON and 35% PRO, 50% CHO, FAT 15% in HP. Total body mass, lean body mass, fat mass and exercise performance (anaerobic power, isokinetic strength, speed and anaerobic endurance) were assessed at the end of the 100% habitual prescribed diet and upon completion of 2 weeks hypoenergetic diet intervention. Results: No significant differences in any measurement of body composition were detected between CON and HP. Total body mass, (CON: -1.1 ± 1.1kg; HP: -1.0 ± 0.7kg, p=0.85) lean body mass (CON: –0.4kg ± 1.1kg; HP: -0.1kg ± 0.7kg, p=0.55) and fat mass (CON: -0.7± 0.6kg; HP -0.9 ± 0.4kg, p=0.43) reductions were observed. Further mechanistic-based inferential statistical analysis observed a potential substantially positive effect (52%) of attenuating lean body mass with higher protein. Exercise performance was maintained throughout the duration of the study independent of dietary protein intake. Conclusion: It is concluded that a high protein intake (35%) compared to a normal protein intake (15%) during energy restriction does not significantly alter body composition or exercise performance in active females during a short term hypoenergetic diet.