Most people involved in the health, fitness, and bodybuilding industry are all too familiar with whey protein, namely whey protein concentrate and whey protein isolate. Both of these whey proteins are considered “fast-digesting” and have a high biological value (100–104). WPC and WPI are typically used pre- and post-training, or anytime someone needs a fast and efficient protein source in their body.

Also highly sought after are the “slower-digesting proteins,” such as calcium caseinate and micellar casein, with a slightly lower biological value than WPC and WPI (77). These milk proteins are highly regarded as “nighttime” proteins for their slow and steady amino acid delivery.

Recently, peptide-based proteins have generated a lot of buzz due to their potential to be rapidly taken up into the bloodstream, virtually bypassing the digestion process. Whey protein hydrolysate and casein hydrolysate (PeptoPro) are two proteins that fall into this category. These hydrolyzed versions of whey and casein contain fragments of protein chains composed of two to three peptides (di- and tripeptides), which are instantaneously absorbed and elevate blood amino acid levels sky high. These hydroproteins are very impressive, but the bitter taste and poor palatability will hold consumers back from making these options a mainstay in their supplement arsenal.


A recent study compared both whey and casein and their effects on muscle protein synthesis (MPS) following resistance training. The study used 17 healthy young males as test subjects. They were devoid of medical ailments and were all in great physical condition. The subjects were randomized to participate in either two protein trials in randomized order or one control trial.

Protein trial group: 9 men. Control trial group: 8 men.

The subjects came into the test facility in a fasted state and underwent heavy resistance training consisting of 10 sets of 8 reps at a predetermined load corresponding to 80% of 1RM. Post-exercise, (within five minutes) the participants consumed either water, casein, or whey protein. The amount of protein ingested was 20 grams dissolved into 400ml of water. Some cool observations were noted:


  • Spiked IGF-1 concentrations instantly and peaked at 30 minutes
  • Spiked insulin concentrations from 15–60 minutes
  • Elicited a stronger myofibrillar FSR increase immediately post-exercise induced a stronger protein synthesis response in the early post-workout period, compared with casein


  • Did not have profound effects on insulin release (compared with whey)
  • Elevated myofibrillar FSR steadily over a six-hour period, as opposed to whey
  • Had better anticatabolic effects than whey protein

The conclusion of the study was obvious in the fact that whey initially spiked MPS immediately and then quickly plummeted downward after the initial spike.

Casein spiked MPS less abruptly with a prolonged elevation as time passed. Immediate intake of whey and casein following heavy resistance resulted in similar MPS response over the subsequent six-hour recovery period.

From my experience, it’s in one’s best interest to utilize a ratio of 70% cold-filtered whey protein isolate plus 20% micellar casein and 10% hydrolyzed whey peptides. Combining both fast- and slow-assimilating, high-quality protein sources provides the benefit of initial high blood amino acid levels and an insulinotropic response from whey protein isolate and hydrolyzed whey peptides, while the micellar casein sustains blood amino acid levels for up to six hours, which elicits an anticatabolic effect.

This is convincing enough for me to recommend 80% of a protein blend made up of of whey isolates and hydrolysates, giving 20% to micellar casein—for its reliable anticatabolic effects from sustained blood amino acid levels.


  • MPS = Muscle Protein Synthesis
  • FSR = Fractional Protein Synthesis Rate
  • WPC = Whey Protein Concentrate
  • WPI = Whey Protein Isolate
  • BV = Biological Value (the % of protein that is absorbed)