Whey vs Casein Protein: Identical Density, Different Job
"Whey vs casein" gets searched 6,600 times a month, and the top results (Healthline, Reddit, examine.com) mostly assume whey simply has more leucine. We ran the two highest-leucine MEASURED SKUs in our database — same evidence grade on both sides, no estimates — through Protein Density, leucine, and DIAAS.
| Metric | Dymatize ISO100 Hydrolyzed Whey Isolate | Dymatize Elite Casein |
|---|---|---|
| Leucine (g/serving) | 2.7g | 2.5g |
| DIAAS | 1.15 | 1.18 |
On measured data — not estimates — whey and casein are functionally identical protein sources by density: both land at 76.9% (Platinum). Leucine per scoop is close too (2.7g vs 2.5g), and both clear the ~2.5g MPS trigger on their own. The real difference isn't protein quality, it's digestion speed and DIAAS: whey digests fast, which is why it's the standard post-workout pick, while casein's micellar structure releases slowly, extending amino acid availability overnight — the reasoning behind the before-bed recommendation. DIAAS gives casein a slight edge (1.18 vs 1.15), reflecting a marginally more complete amino profile once digested. Pick whey around training and casein before sleep — not because one beats the other, but because they're suited to different clocks.
What's your number?
Protein Density only matters relative to your daily target. Calculate yours, then use it to decide what's worth ordering.