Evenly Distributed Protein Intake over 3 Meals Augments Resistance Exercise–Induced Muscle Hypertrophy in Healthy Young Men

Jun Yasuda,Toshiki Tomita,Takuma Arimitsu,Satoshi Fujita

doi:10.1093/jn/nxaa101

Abstract

ABSTRACTBackgroundAlthough daily protein intake (PI) has been reported to be essential for regulating muscle mass, the distribution of daily PI in individuals is typically the lowest at breakfast and skewed toward dinner. Skewed protein intake patterns and inadequate PI at breakfast were reported to be negative factors for muscle maintenance.ObjectivesThis study examined whether a protein-enriched meal at breakfast is more effective for muscle accretion compared with the typical skewed PI pattern.MethodsThis 12-wk, parallel-group, randomized clinical trial included 26 men (means ± SEs; age: 20.8 ± 0.4 y; BMI: 21.8 ± 0.4 kg/m2). The “high breakfast” (HBR) group (n = 12) consumed a protein-enriched meal at breakfast providing a PI of 0.33 g/kg body weight (BW); their PI at lunch (0.46 g/kg BW) and dinner (0.48 g/kg BW) provided an adequate overall daily PI (1.30 g/kg BW/d). The “low breakfast” (LBR) group (n = 14) consumed 0.12 g protein/kg BW at breakfast; intakes at lunch (0.45 g/kg BW) and dinner (0.83 g/kg BW) yielded the same daily PI as in the HBR group. The participants performed supervised resistance training (RT) 3 times per week (75–80% 1-repetition maximum; 3 sets × 10 repetitions). DXA was used to measure the primary outcome variable, that is, total lean soft tissue mass (LTM).ResultsThe total LTM at baseline did not differ between the HBR (52.4 ± 1.3 kg) and LBR (53.4 ± 1.2 kg) groups. After the intervention, increases in total LTM were significant in both groups, with that in the HBR group (2.5 ± 0.3 kg) tending to be greater than that in the LBR group (1.8 ± 0.3 kg) (P = 0.06), with a large effect size (Cohen d = 0.795).ConclusionsFor RT-induced muscle hypertrophy in healthy young men, consuming a protein-enriched meal at breakfast and less protein at dinner while achieving an adequate overall PI is more effective than consuming more protein at dinner.This study was registered at University hospital Medical Information Network (UMIN) Clinical Trials Registry as UMIN000037583 (https://upload.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000042763).

Highlights

Reduced muscle mass has been reported to be associated with health conditions such as diabetes [1], metabolic syndrome [2], and sarcopenia [3]
We considered the compliance of consuming provided meals to be reliable based on the check sheets, which showed >95% compliance in both groups (HBR group: 96.7 ± 0.9%; low breakfast” (LBR) group: 95.7 ± 0.9%) for the entire period
This is the first study to describe that having adequate protein intake (PI) (>0.24 g/kg body weight (BW)) at all 3 meals by adding a high-protein breakfast was more effective in increasing muscle mass in healthy young participants than a typical PI pattern, while maintaining a daily total PI that was not significantly different between the 2 groups (P = 0.236)

Summary

Introduction

Reduced muscle mass has been reported to be associated with health conditions such as diabetes [1], metabolic syndrome [2], and sarcopenia [3]. Protein intake (PI) has been reported as the key factor for the regulation of muscle mass [9–19], and the pattern of daily PI in individuals is found to be typically lowest at breakfast and skewed toward dinner [13, 20, 21]. Daily protein intake (PI) has been reported to be essential for regulating muscle mass, the distribution of daily PI in individuals is typically the lowest at breakfast and skewed toward dinner. The “high breakfast” (HBR) group (n = 12) consumed a protein-enriched meal at breakfast providing a PI of 0.33 g/kg body weight (BW); their PI at lunch (0.46 g/kg BW) and dinner (0.48 g/kg BW) provided an adequate overall daily PI (1.30 g/kg BW/d).

Objectives

Results

Conclusion