Whey protein has had a monopoly on the "serious about muscle" conversation for decades. But the research doesn't actually back that up — plant protein isn't the compromise choice it's made out to be.

A 2015 study published in the Journal of the International Society of Sports Nutrition put this to the test directly. Over 12 weeks of resistance training, one group supplemented with pea protein isolate, another with whey. The result: both groups saw comparable gains in muscle thickness — pea protein promoted a significantly greater increase in muscle thickness than a placebo, with no meaningful difference from whey. As the study's own authors put it, pea protein "could be used as efficiently as whey" for muscle thickness gains during resistance training.

So what actually matters?

Two things: getting enough total protein across the day, and covering your essential amino acids. Whey happens to be a complete protein on its own. Plant sources can get there too — pea protein is naturally lower in one or two amino acids, but pairing it with rice protein (which covers what pea lacks) closes that gap. That's exactly why most well-formulated plant protein powders use a pea + rice blend instead of a single source.

If you're training and wondering whether to make the switch, the amino acid math works out — you just have to pick the right blend.

Explore your options: Shop Plant Protein Powders — pea, rice, hemp, soy, and peanut protein sources across the ButNotMeat marketplace.