We must once again look to the works from Dr. Antonio (2) on the effects of a high protein diet on indices of health and body composition (a crossover trial in resistance-trained men.) The study was eight weeks of a high protein diet (>3 g/kg/day) coupled with a periodized heavy resistance training program has been shown to positively affect body composition with no deleterious effects on health. Using a randomized, crossover design, resistance-trained male subjects underwent a 16-week intervention (i.e., two 8-week periods) in which they consumed either their normal (i.e., habitual) or a higher protein diet (>3 g/kg/day). Thus, the purpose of this study was to ascertain if significantly increasing protein intake would affect clinical markers of health (i.e., lipids, kidney function, etc.) as well as performance and body composition in young males with extensive resistance training experience. Twelve healthy resistance-trained men volunteered for this study (mean ± SD: age 25.9 ± 3.7 years; height 178.0 ± 8.5 cm; years of resistance training experience 7.6 ± 3.6) with 11 subjects completing most of the assessments. In a randomized crossover trial, subjects were tested at baseline and after two 8-week treatment periods (i.e., habitual [normal] diet and high protein diet) for body composition, measures of health (i.e., blood lipids, comprehensive metabolic panel) and performance. Each subject maintained a food diary for the 16-week treatment period (i.e., 8 weeks on their normal or habitual diet and 8 weeks on a high protein diet). Each subject provided a food diary of two weekdays and one weekend day per week. In addition, subjects kept a diary of their training regimen that was used to calculate total work performed. During the normal and high protein phase of the treatment period, subjects consumed 2.6 ± 0.8 and 3.3 ± 0.8 g/kg/day of dietary protein, respectively. The mean protein intake over the 4-month period was 2.9 ± 0.9 g/kg/day. The high protein group consumed significantly more calories and protein (p < 0.05) than the normal protein group. There were no differences in dietary intake between the groups for any other measure. Moreover, there were no significant changes in body composition or markers of health in either group. There were no side effects (i.e., blood lipids, glucose, renal, kidney function etc.) regarding high protein consumption. In resistance-trained young men who do not significantly alter their training regimen, consuming a high protein diet (2.6 to 3.3 g/kg/day) over a 4-month period has no effect on blood lipids or markers of renal and hepatic function. Nor were there any changes in performance or body composition. This is the first crossover trial using resistance-trained subjects in which the elevation of protein intake to over four times the recommended dietary allowance has shown no harmful effects.
Dr. Jose Antonio’s research continues. This study (3) looked at the consumption of a high protein diet (>4 g/kg/d) in trained men and women who did not alter their exercise program. Thus, the purpose of this investigation was to determine if a high protein diet in conjunction with a periodized heavy resistance training program would affect indices of body composition, performance and health. Forty-eight healthy resistance-trained men and women completed this study (mean ± SD; Normal Protein group [NP n = 17, four female and 13 male]: 24.8 ± 6.9 yr; 174.0 ± 9.5 cm height; 74.7 ± 9.6 kg body weight; 2.4 ± 1.7 yr of training; High Protein group [HP n = 31, seven female and 24 male]: 22.9 ± 3.1 yr; 172.3 ± 7.7 cm; 74.3 ± 12.4 kg; 4.9 ± 4.1 yr of training). Moreover, all subjects participated in a split-routine, periodized heavy resistance-training program. Training and daily diet logs were kept by each subject. Subjects in the NP and HP groups were instructed to consume their baseline (~2 g/kg/d) and >3 g/kg/d of dietary protein, respectively. Subjects in the NP and HP groups consumed 2.3 and 3.4 g/kg/day of dietary protein during the treatment period. The NP group consumed significantly (p < 0.05) more protein during the treatment period compared to their baseline intake. The HP group consumed more (p < 0.05) total energy and protein during the treatment period compared to their baseline intake. Furthermore, the HP group consumed significantly more (p < 0.05) total calories and protein compared to the NP group. There were significant time by group (p ≤ 0.05) changes in body weight (change: +1.3 ± 1.3 kg NP, −0.1 ± 2.5 HP), fat mass (change: −0.3 ± 2.2 kg NP, −1.7 ± 2.3 HP), and % body fat (change: −0.7 ± 2.8 NP, −2.4 ± 2.9 HP). The NP group gained significantly more body weight than the HP group; however, the HP group experienced a greater decrease in fat mass and % body fat. There was a significant time effect for FFM; however, there was a non-significant time by group effect for FFM (change: +1.5 ± 1.8 NP, +1.5 ± 2.2 HP). Furthermore, a significant time effect (p ≤ 0.05) was seen in both groups vis a vis improvements in maximal strength (i.e., 1-RM squat and bench) vertical jump and pull-ups; however, there were no significant time by group effects (p ≥ 0.05) for all exercise performance measures. Additionally, there were no changes in any of the blood parameters (i.e., basic metabolic panel). They concluded by stating “consuming a high protein diet (3.4 g/kg/d) in conjunction with a heavy resistance-training program may confer benefits with regards to body composition. Furthermore, there is no evidence that consuming a high protein diet has any deleterious effects.”
References
- A High Protein Diet Has No Harmful Effects: A One-Year Crossover Study in Resistance-Trained Males. Jose Antonio, Anya Ellerbroek, Tobin Silver, Leonel Vargas, Armando Tamayo, Richard Buehn, and Corey A. Peacock. Exercise and Sport Science Laboratory, Nova Southeastern University, Davie, FL, USA. 2016. (https://www.hindawi.com/journals/jnme/2016/9104792/)
- The effects of a high protein diet on indices of health and body composition – a crossover trial in resistance-trained men. Jose Antonio, Anya Ellerbroek, Tobin Silver, Leonel Vargas and Corey Peacock. Journal of the International Society of Sports Nutrition. 2016 (https://jissn.biomedcentral.com/articles/10.1186/s12970-016-0114-2)
- A high protein diet (3.4 g/kg/d) combined with a heavy resistance training program improves body composition in healthy trained men and women – a follow-up investigation. Jose Antonio, Anya Ellerbroek, Tobin Silver, Steve Orris, Max Scheiner, Adriana Gonzalez and Corey A Peacock. Journal of the International Society of Sports Nutrition. 2015 (https://jissn.biomedcentral.com/articles/10.1186/s12970-015-0100-0)
- International Society of Sports Nutrition position stand: protein and exercise. Bill Campbell, Richard B Kreider, Tim Ziegenfuss, Paul La Bounty, Mike Roberts, Darren Burke, Jamie Landis, Hector Lopez and Jose Antonio. Journal of the International Society of Sports Nutrition. 2007 (https://jissn.biomedcentral.com/articles/10.1186/1550-2783-4-8)
- Protein requirements and muscle mass/strength changes during intensive training in novice bodybuilders. P. W. Lemon, M. A. Tarnopolsky, J. D. MacDougall, S. A. Atkinson. J Appl Physiol (1985) (https://www.ncbi.nlm.nih.gov/pubmed/1400008)
- Protein requirements and muscle mass/strength changes during intensive training in novice bodybuilders. P. W. Lemon, M. A. Tarnopolsky, J. D. MacDougall, S. A. Atkinson. J Appl Physiol (1985) (https://www.ncbi.nlm.nih.gov/pubmed/1400008)
- Exercise-induced changes in protein metabolism. K. D. Tipton, R. R. Wolfe. Acta Physiol Scand. 1998 (https://www.ncbi.nlm.nih.gov/pubmed/9578384)
- Muscle protein synthesis in response to nutrition and exercise. P. J. Atherton, K. Smith. The Journal of Physiology. 2012 (http://onlinelibrary.wiley.com/doi/10.1113/jphysiol.2011.225003/abstract)
- Beyond the zone: protein needs of active individuals. P. W. Lemon. J Am Coll Nutr. 2000 (https://www.ncbi.nlm.nih.gov/pubmed/11023001)
- Meta-analysis of nitrogen balance studies for estimating protein requirements in healthy adults. William M. Rand, Peter L. Pellett, Vernon R. Young. Am J Clin Nutr. 2003 (https://www.ncbi.nlm.nih.gov/pubmed/12499330)
