More protein, resistance training required for optimal muscle mass enhancement

Protein supplementation is effective for increasing lean body mass (LBM) and increasing current intake by as little as 0.1 g/kg of body weight per day (BW/d) may potentially improve or sustain current muscle mass, according to a systematic review and meta-analysis. This effect diminishes after exceeding a certain amount, but resistance training helps suppress the decline.

The meta-analysis included 105 articles describing trials evaluating the effects of protein intake on LBM. These trials comprised 138 intervention groups and 5,402 participants. Fifty-three articles reported on 72 interventions with resistance training (n=2,325), 56 described 66 interventions without training (n=3,077), and four articles involved interventions both with and without training.

Multivariate-adjusted spline model revealed that LBM could increase or be maintained by increasing current protein intake for several months by 0.1 g/kg/d. The increase occurred in a dose-dependent manner over a dose range of 0.5–3.5 g/kg/d.

Specifically, an increase in protein intake of 0.1 g/kg BW/d was associated with a mean augmentation in LBM of 0.39 kg and 0.12 kg below and above the total protein intake of 1.3 g/kg/d, respectively. Furthermore, above this threshold, the rate of increase in LBM rapidly declined, which could be suppressed by resistance training.

In light of the findings, upping protein intake and resistance training is recommended to optimally augment LBM.