Essential amino acids (EAAs) contribute to the regulation of muscle synthesis. Whey protein, which contains a higher amount of these essential amino acids, can have a significant impact on muscle synthesis. However, currently, there is insufficient data on the effects of soy and whey protein supplements on body composition.
The authors of a study published in the British Journal of Nutrition aimed to conduct a meta-analysis of existing randomized clinical trials that examined the effects of whey and soy protein supplements on body composition (lean mass, fat mass, body weight, and percentage of body fat) in adults.
A search was conducted in the PubMed, Scopus, and Google Scholar databases up until August 2020 to find all relevant published articles evaluating the addition of soy protein and whey protein on body composition parameters. In the end, ten studies with 596 participants were included in the meta-analysis.
Significant increases in lean body mass were observed after whey protein consumption. There were no significant changes in body weight, fat mass, and percentage of body fat with whey protein intake. Similarly, no significant effects on body composition parameters were found with soy protein intake.
The authors concluded that whey protein intake significantly improved body composition by increasing lean body mass without affecting fat mass, overall body weight, and percentage of body fat. However, such effects were not observed with soy protein intake.