Is there a beneficial effect of a high-protein diet on body composition and strength capacity in physical active middle-aged individuals?-An eight-week randomized controlled trial.

Introduction: Demographic changes are resulting in a continual increase in the proportion of individuals over 65 years old. Simultaneously, muscle mass (MM) tends to decrease with age, with a decline noticeable from the middle of the fourth decade of life. While physical activity is considered a modulator for maintaining MM, the interaction with nutrient uptake, especially protein intake, is getting more into focus. Due to a lack of data on the effect of a high-protein diet on middle-aged individuals (40-65 years), this study aimed to investigate the influence of a high-protein diet in middle-aged physically active persons on body composition and performance. Methods: Using stratified randomization, participants were allocated to either a high-protein group (>2.3 g/kg FFM/day) ( Results: No significant differences in energy intake were found between the groups ( Discussion: Our results indicate no to only trivial effects of adding a high-protein diet to otherwise physically active middle-aged individuals. Trivial effects could be seen for an increase in muscle strength after this eight-week intervention. However, MM and FFM were not significantly affected. Based on the small effect sizes we observed in our results we do not see a benefit of a high-protein diet on body composition and strength capacity without altering the exercise habits.