Soy protein or Whey protein?

Both items are reviewed in the reference. Below their characteristics sit side by side as the studies describe them. This is a comparison of data, not advice on what to choose.

	Soy protein	Whey protein
evidence level	B	A
Sources in the review	2	6
Category	Base	Base
Goals	Mass, Strength, Recomposition	Mass, Strength, Recomposition, Fat loss
Dosage	20-40 g per serving; the daily guideline is 1.6-2.2 g/kg. In the meta-analysis the comparison was at the usual servings of 20-25 g.	20-40 g per serving depending on body weight; daily protein 1.6-2.2 g/kg for muscle growth, up to 2.4 g/kg with a calorie deficit. Forms: concentrate, isolate, hydrolyzate.
When to take	The timing is secondary. Usually 20-40 g within a few hours after training; distribution over 3-4 servings works no worse.	The timing is secondary: the total protein per day matters more than the "anabolic window". 2-4 servings of 0.4 g/kg distributed evenly during the day.

The conclusion from the data. In the reference «Whey protein» Level A and 6 sources, while «Soy protein» — Level B and 2. A higher level means the effect is better supported by research, not that the item suits you better.

Verdicts

Soy protein

A complete protein: in a meta-analysis of nine studies it was not inferior to animal proteins

Whey protein

Tops up daily protein; the source of protein matters less than its total amount

Sources for both items

Other comparisons

Creatine monohydrate or Creatine HCl Creatine monohydrate or Creatine nitrate Whey protein or Casein protein Whey protein or Pea protein Pea protein or Rice protein BCAA (branched-chain amino acids) or Essential amino acids (EAA) Citrulline malate or Arginine Caffeine or Caffeine in chewing gum