Whey Protein vs Soy Protein Isolate
Per 100 g, whey protein gives 80 g protein for 400 calories, while soy protein isolate gives 88 g for 370. Here is the full breakdown, including which one gives more protein per calorie.
| Per 100 g | Whey Protein | Soy Protein Isolate |
|---|---|---|
| Protein | 80 g | 88 g |
| Calories | 400 | 370 |
| Carbs | 8 g | 0 g |
| Fats | 6 g | 3 g |
| Protein density | 80% | 95% |
Which should you pick?
- Cutting or high-protein dieting: Soy Protein Isolate — more protein per calorie.
- Bulking or hard training days: Whey Protein packs more calories into the same volume, which helps when appetite is the limit.
- Lowest carbs: Soy Protein Isolate at 0 g per 100 g.
- Lowest fat: Soy Protein Isolate at 3 g per 100 g.
Frequently asked questions
- Which has more protein, whey protein or soy protein isolate?
- Soy Protein Isolate has more protein — 88 g per 100 g versus 80 g.
- Which is lower in calories?
- Soy Protein Isolate is lighter at 370 kcal per 100 g, compared with 400 kcal.
- Which is better for cutting?
- Soy Protein Isolate — about 95% of its calories come from protein, versus 80% for the other. In a deficit, protein per calorie is the number that matters.
- Can I swap whey protein for soy protein isolate in a meal?
- Yes, but match the macros rather than the weight. To keep protein equal, scale the portion by the ratio of their protein per 100 g — the Procaaf calculator does this for you when you load both foods and adjust the grams.