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.
Study Goal
The researchers aimed to determine if a high-protein diet (>3 g/kg/d) combined with heavy resistance training affects body composition, performance, and health in trained individuals.
Results Summary
The high-protein group showed greater reductions in fat mass and body fat percentage compared to the normal-protein group, though both groups improved strength similarly. No adverse effects on blood parameters were observed.
Population
48 healthy resistance-trained men and women (mean age ~23-25 years, training experience 2.4-4.9 years).
Effective Dosage
High-protein group: 3.4 g/kg/d; normal-protein group: 2.3 g/kg/d.
Duration
Not specified in the abstract.
Interactions
None mentioned.
| Intervention | Direction | Endpoint | Population | Dosage | Impact | Claim # |
|---|---|---|---|---|---|---|
high protein diet (>4 g/kg/d) | no change | body composition | trained men and women who did not alter their exercise program | no significant effect | has been previously shown to have no significant effect | #1 |
high protein diet in conjunction with a periodized heavy resistance training program | neutral | indices of body composition, performance and health | healthy resistance-trained men and women | - | would affect | #2 |
high protein diet (3.4 g/kg/d) in conjunction with a heavy resistance-training program | neutral | body composition | - | - | may confer benefits with regards to | #3 |
high protein diet | no change | - | - | no evidence | has no deleterious effects | #4 |
Normal Protein group (2.3 g/kg/day) | increase | body weight | healthy resistance-trained men and women | +1.3 ± 1.3 kg | gained significantly more | #5 |
High Protein group (3.4 g/kg/day) | decrease | fat mass | healthy resistance-trained men and women | -1.7 ± 2.3 kg | experienced a greater decrease in | #6 |
High Protein group (3.4 g/kg/day) | decrease | % body fat | healthy resistance-trained men and women | -2.4 ± 2.9 | experienced a greater decrease in | #7 |
Normal Protein group (2.3 g/kg/day) | no change | FFM | healthy resistance-trained men and women | +1.5 ± 1.8 | non-significant time by group effect for | #8 |
High Protein group (3.4 g/kg/day) | no change | FFM | healthy resistance-trained men and women | +1.5 ± 2.2 | non-significant time by group effect for | #9 |
high protein diet | no change | all exercise performance measures | healthy resistance-trained men and women | no significant effects | no significant time by group effects | #10 |
high protein diet | no change | any of the blood parameters (i.e., basic metabolic panel) | healthy resistance-trained men and women | no changes | no changes in | #11 |
BACKGROUND: The consumption of a high protein diet (>4 g/kg/d) in trained men and women who did not alter their exercise program has been previously shown to have no significant effect on body composition. 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. METHODS: 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. RESULTS: 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). CONCLUSION: 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.