BCAAs vs. Whey Protein Powder: What's the Difference? BCAAs and whey protein powder are dietary supplements touted for their muscle-building capabilities and are integral in supporting muscle protein synthesis, a key factor in achieving lean muscle mass and fitness goals. Understanding the benefits and limitations of these supplements is crucial in determining the best option for individual dietary and fitness needs. David Robinson, PhD UK Fitness ProJan 15 · 12 min read