Benefits of Protein (Whey & Casein)

Evidence-Based Benefits

• Muscle protein synthesis — Tang et al. (2009) showed whey protein stimulated MPS 31% more than casein and 18% more than soy at rest, with greater differences after resistance exercise due to faster aminoacidemia
• Lean mass — Morton et al. (2018) meta-analysis of 49 RCTs (1863 participants) found protein supplementation significantly increased lean mass (+0.3 kg) and lower-body strength during resistance training
• Leucine content — whey contains ~11% leucine by weight, the highest of any common protein source; 2.5-3 g leucine per serving maximally triggers mTOR activation and MPS
• Overnight recovery (casein) — Res et al. (2012) demonstrated 40 g casein before sleep increased overnight muscle protein synthesis by 22% and improved whole-body protein balance in young men

What the Research Says

Whey and casein protein are among the most extensively studied supplements in sports science, with hundreds of RCTs and multiple meta-analyses confirming their efficacy. The key finding from Morton et al. (2018) — the largest meta-analysis to date — is that protein supplementation augments resistance training adaptations, but total daily protein intake matters far more than timing, source, or type. The practical protein dose-response plateaus at ~1.6 g/kg/day, with an upper confidence bound of ~2.2 g/kg. Whey is superior to casein, soy, and most plant proteins for acute MPS stimulation, primarily due to faster digestion and higher leucine content. Casein has a unique niche for overnight protein delivery.

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