PES Select Protein Snickerdoodle 4 lbs. Phase 1: by enhancing the blend with pre-digested leucine peptides, we allow for blood levels of leucine to spike, which then spikes muscle protein synthesis and lean muscle building. Phase 2: whey protein comes in next and gives your body the other essential amino acids. Phase 3: casein protein finishes the job by sustaining lean muscle accrual for hours