We are overwhelmed with various protein sources including whey protein, casein, BCAAs, EAAs, soy protein, rice protein and many more. Each one is trying to make their case as to why they are the optimal protein type. Some claim superiority for ethical reasons (mainly plant proteins), others claim superiority for being optimal stimulators of muscle protein synthesis or MPS (mainly whey, BCAAs and EAAs), and others for prolonged release of protein in the gut (casein).
We have to ask ourselves what our goal is and for most bodybuilders the goal is to maximize muscle built. We want to know which protein type is best at improving our BODY COMPOSITION, and unfortunately few studies choose to measure body composition, and instead focus on MPS, and we have previously discussed how MPS doesn’t acutely correlate to long term increases in muscle mass.
What the science is clear on is that more protein is better for building muscle. However, the science isn’t clear on if one source is better than another when it comes to BODY COMPOSITION. An 8-weeek study comparing supplementation with whey protein to rice protein with resistance exercise, found that both had equally beneficial impacts on lean body mass, body fat, and ultrasound measured muscle thickness.
Though animal protein sources do have better bioavailability and denser protein content, you will likely get what you need as long as you don’t completely exclude animal sources. If you want to go full veg bodybuilder, 30% of your calories should be protein to make sure you get enough BCAAs, in which case a protein supplement is recommended (rice or whey ?) .
Gilbert JA et al. Effect of proteins from different sources on body composition. Nutr Metab Cardiovasc Dis. 2011 Sep;21 Suppl 2:B16-31.
Joy, Jordan M et al. The Effects of 8 Weeks of Whey or Rice Protein Supplementation on Body Composition and Exercise Performance. Nutrition Journal 12 (2013): 86. PMC. Web. 11 Feb. 2017.
Chalvon-Demersay T. A Systematic Review of the Effects of Plant Compared with Animal Protein Sources on Features of Metabolic Syndrome. J Nutr. 2017 Jan 25.