The effects of consuming a high protein diet (4.4 g/kg/d) on body composition in resistance-trained individuals

Abstract

Background

The consumption of dietary protein is important for resistance-trained individuals. It has been posited that intakes of 1.4 to 2.0 g/kg/day are needed for physically active individuals. Thus, the purpose of this investigation was to determine the effects of a very high protein diet (4.4 g/kg/d) on body composition in resistance-trained men and women.

Methods

Thirty healthy resistance-trained individuals participated in this study (mean ± SD; age: 24.1 ± 5.6 yr; height: 171.4 ± 8.8 cm; weight: 73.3 ± 11.5 kg). Subjects were randomly assigned to one of the following groups: Control (CON) or high protein (HP). The CON group was instructed to maintain the same training and dietary habits over the course of the 8 week study. The HP group was instructed to consume 4.4 grams of protein per kg body weight daily. They were also instructed to maintain the same training and dietary habits (e.g. maintain the same fat and carbohydrate intake). Body composition (Bod Pod®), training volume (i.e. volume load), and food intake were determined at baseline and over the 8 week treatment period.

Results

The HP group consumed significantly more protein and calories pre vs post (p < 0.05). Furthermore, the HP group consumed significantly more protein and calories than the CON (p < 0.05). The HP group consumed on average 307 ± 69 grams of protein compared to 138 ± 42 in the CON. When expressed per unit body weight, the HP group consumed 4.4 ± 0.8 g/kg/d of protein versus 1.8 ± 0.4 g/kg/d in the CON. There were no changes in training volume for either group. Moreover, there were no significant changes over time or between groups for body weight, fat mass, fat free mass, or percent body fat.

Conclusions

Consuming 5.5 times the recommended daily allowance of protein has no effect on body composition in resistance-trained individuals who otherwise maintain the same training regimen. This is the first interventional study to demonstrate that consuming a hypercaloric high protein diet does not result in an increase in body fat.

Keywords:

• Protein
• Diet
• Body composition
• Exercise
• Supplements

Acknowledgement

We would like to thank Dr. Jordan Moon of MusclePharm® and Eric Hillman of Europa® Sports Products (Adept Nutrition) for kindly providing protein powder. Also, we would like to thank Jennie Von Doellen, Kat Fleming and Rachael Tutunick for helping with the data collection.

Competing interests

JA is the CEO of the International Society of Sports Nutrition. The protein powder was provided by MusclePharm® and Adept Nutrition (Europa® Sports Products brand); both are sponsors of the ISSN conferences.

Authors’ contributions

JA (corresponding author) was responsible for the study design, the statistical analysis and the writing of the manuscript. AE and BF was involved in the execution of the measurements. CP and TS provided assistance in the study design, statistical analysis and editing of the manuscript. All authors read and approved the final manuscript.