Nowadays, ketogenic diet (KD) is widely used in body aesthetics for changing body composition, even though there is a lack of research regarding to the possible benefits on muscle hypertrophy.
PURPOSE: The purpose of this study was to evaluate the efficacy of an 8-week KD during energy surplus and a resistance training protocol on muscle hypertrophy in trained men.
METHODS: 24 healthy men (age 30 ± 4.7 years; weight 76.7 ± 8.2 kg; height 174.3 ± 19.7 cm; > 2 years of consecutive training experience) performed an 8-week resistance training (RT) program with similar hypertrophy training variables. Participants were randomly assigned to either a KD (10:20:70, n=9), or a non-ketogenic diet (55:20:25, n=10, NKD), or a control group (n=5, CG) in hypercaloric condition (39 kcal · kg−1 · d−1). Body composition changes were measured by dual energy X-ray absorptiometry (DXA) before and after each nutritional intervention and training program in all participants. Compliance with the ketosis state was monitored by measuring urinary ketones weekly. Statistical evaluations to determine significant differences between groups and substantive significance were performed with paired t-test, where critical α was p < 0.05, and Cohen’s d effect size (ES), respectively.
RESULTS: There was a significant reduction in fat mass (Δ= -10.4%, p =0.030, ES = 0.46) and abdominal visceral adiposity in KD (Δ= -16.3%, p =0.008; ES = 0.84); while no significant changes were observed in the NKD and CG groups. Muscle mass significantly increased after 8 weeks of RT program in the NKD group only (Δ=+2.1%, p <0.01, ES = 0.31).
CONCLUSIONS: Our results suggest that KD can be helpful for decreasing abdominal visceral adiposity and fat mass, but not to increase muscle mass during positive energy balance in men undergoing RT. This study shows the relevance of macronutrient manipulation in RT programs, in order to improve body composition parameters focusing on training goals (fat reduction and/or increase of muscle mass) in trained men.
Supported by University of Málaga (Campus of International Excellence Andalucía Tech).