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

Jose Antonio,Tobin Silver,Brandon Fromhoff,Corey A Peacock,Anya Ellerbroek

doi:10.1186/1550-2783-11-19

Abstract

BackgroundThe 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.MethodsThirty 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.ResultsThe 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.ConclusionsConsuming 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.

Highlights

Protein is the most important macronutrient vis-à-vis positive alterations in body composition
The average US adult consumes slightly more than the recommended daily allowance (RDA); this level is inadequate for athletes or active individuals who engage in exercise/sport training for several hours per week
Of the 10, three stated an inability to consume the protein needed for the study and one subject complained of gastrointestinal distress

Summary

Introduction

Protein is the most important macronutrient vis-à-vis positive alterations in body composition. Previous work has suggested that protein intakes in the range of 1.2-2.0 grams per kilogram (kg) body weight per day (g/kg/d) are needed in active individuals [1,2,3,4,5,6,7]. The average protein intake for US adults is 91 grams daily or ~1.0 g/kg ideal body weight [8]. Consuming more than the RDA may be considered a ‘high’ intake of protein [9]. The consumption of dietary protein is important for resistance-trained individuals. 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

Results

Conclusion