Whey vs plant protein
Whey, by a small margin: in trials soy protein matched dairy protein for muscle gain, while other plant proteins did slightly worse.
Side by side
| Whey | Plant protein | |
|---|---|---|
| Leucine per 25 g scoop | About 2.7 g | About 1.8 to 2.2 g, depending on the blend |
| Muscle gain over months | Slightly ahead of most plant proteins | Soy matches dairy; rice, oat and potato protein fell slightly behind |
| Strength gains | No difference in trials | No difference in trials |
| Amino acid profile | Complete, high in leucine | Single sources are short on lysine or methionine; blends fix this |
| Dose to match | 25 g | About 30 to 40 g for the same leucine |
| Digestion | Problems if you are lactose intolerant | No dairy, generally easier |
| Cost per 25 g protein | Usually cheaper | Usually dearer |
| Taste and mixability | Smooth | Chalkier, though blends have improved |
Which one
Whey
Default to whey if you tolerate dairy and want the cheapest reliable option.
Plant protein
Choose plant protein if you avoid dairy: soy performs like dairy protein, and with other plant powders a slightly bigger scoop gives you the same leucine.
What matters more
Hit your daily protein total first. The difference between two protein powders is much smaller than the difference between reaching that total and falling short of it.
Run the numbers
Sources2
- Reid-McCann, R.J. et al. (2025). Effect of Plant Versus Animal Protein on Muscle Mass, Strength, Physical Performance, and Sarcopenia: A Systematic Review, Meta-Analysis and Meta-Regression. Nutr Rev 83(7).43 trials: plant protein gave slightly less muscle gain overall, soy matched milk protein, and strength did not differ.
- Morton, R.W. et al. (2018). A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. Br J Sports Med 52(6).Gains from extra protein levelled off at about 1.6 g/kg of total daily protein.