For strong middle-aged adults, eating more protein doesn't lead to extra muscle-growth

Katherine Hager
·2-min read
Photo credit: luza studios - Getty Images
Photo credit: luza studios - Getty Images

From Runner's World


A study was published in the American Journal of Physiology: Endocrinology and Metabolism and comprehensively investigated the effects of diet and resistance training on middle-aged adults.

Colleen McKenna, a graduate student in the division of nutritional sciences and registered dietician at the University of Illinois Urbana-Champaign and kinesiology and community health professor Nicholas Burd examined if the American Food and Nutrition’s Boards recommended daily allowance of protein — 1.1 to 1.2 grams of protein per kilogram of body weight per day — could be doubled to see an increase in muscle gain.

In the study, 50 middle-aged adults followed a protein-strict diet for 10 weeks. The group was divided into two, the moderate-protein group consumed 1.2 grams of protein per kilogram of body weight per day. The high-protein group consumed 1.6 grams per kilogram per day.

The study kept calories equivalent in the meals provided to the two groups with additions of beef tallow and dextrose. Researchers fed each person a minced beef steak and a carbohydrate beverage after every training session and sent participants home with an isolated protein drink to be consumed every night for the duration of the 10-week study.

It was hypothesised that getting high-quality protein and consuming more protein than the AMFB suggests whilst engaging in resistance training would aid in muscle growth. But, by the end of the 10 weeks, the research team saw no significant change, all the biomarkers of health, (fat, body mass, glucose tolerance, kidney function, bone density) were all roughly the same.

When it came to the end of the 10-week testing phase, no major changes were detected amongst participants, suggesting that more protein doesn't equate with even more gains. 'It didn't increase lean mass more than eating a moderate amount of protein. We didn't see more fat loss, and body composition was the same between the groups,' said Burd. 'They got the gain in weight, but that weight gain was namely from lean-body-mass gain.'

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