Extra protein from food or supplements does lead to increases in strength and muscle, but not as much as some might hope, say researchers from McMaster University in Ontario, Canada.
Their results are based on a review of data from 49 randomized controlled trials in 17 countries and more than 1,800 participants.
The upshot: supplementing protein while doing resistance training can increase strength by about 9% and add about one pound of muscle. The effect levels off at a certain point, after which extra protein provides no additional benefit.
About the research
The research team conducted a systematic review and meta-analysis of research published on the topic of protein supplementation and resistance training, looking at how much extra muscle men and women gained, as well as how much stronger they became.
The studies had to be at least six weeks long, include resistance training at least twice a week, and one group had to be given a protein supplement that didn’t have other muscle-building ingredients such as creatine or testosterone-enhancing compounds. Ten of the studies involved people who were experienced in resistance training and 14 studies had exclusively female participants.
Small muscle benefits, mostly in people already training
The team found that protein supplementation led to an increase in muscle, but not much. In addition, protein supplements were more effective in people who were already lifting weights and less effective in people over age 60.
The analysis didn’t find any differences between types of protein supplements or a distinction between getting protein from food or from supplements.
How much extra protein builds muscle?
When the team analyzed the relationship between the amount of muscle gained and total amount of dietary protein consumed, they found that gains leveled off at around 1.6 grams of protein per kilogram of body weight per day, or about 0.7 grams per pound. That’s twice the recommended daily amount in most official nutrition guidelines, they note.
“Going to the gym is where most of the benefits come from,” the lead researcher said.
Current studies are investigating the key amino acids in protein that aid this muscle-building process, particularly leucine, and especially for adults over age 60 who may have muscle and bone loss known as sarcopenia.
Future studies will focus on ways to boost muscle mass and the effect of protein supplementation in older adults, including through everyday foods such as milk and meat.
Source: British Journal of Sports Medicine, September 6, 2019.
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