Formulated from science. Targeted whey/casein blend. Ultra-pure milk protein isolate. Premium WPC-80. Know your protein! Do you just whey? If you're a regular whey user, there's something you need to know. When it comes to optimally building lean muscle, just whey protein is not enough. Nature had it right. When researchers tested a combination of whey protein + casein protein, as found naturally in milk protein, they discovered that the two protein sources work together in a synergetic manner to build lean muscle. 100% whey protein in isolation only gets you so far...it can spike protein synthesis with an influx of amino acids, but quickly returns to baseline, leaving you where you started. Enter casein, a slower digesting protein that typically consumed for its anti-catabolic properties as it promotes a steady release of amino acids over time. In another published study, researchers found the combination of whey protein with casein protein resulted in a quick release in protein synthesis along with a sustained elevation in plasma leucine levels. Plasma leucine levels are a key dictator of muscle protein synthesis, and thus, a combination of whey protein and casein protein may serve to maximize muscle protein accumulation.