Whey comes from a by-product of cheese production, the thin layer of liquid on top of the cheese. It only takes 20 minutes for all of the whey consumed to be widespread in your bloodstream. After 20-40 minutes the level of the amino acids in your bloodstream has reached its peak and within the hour it will have completed all of its metabolic processes, either oxidation or protein synthesis. After a single feeding of protein your amino acid levels will quickly return to normal.
Is this speed a good thing? YES! Muscle growth is hugely dependent on a healthy balance between protein breakdown and synthesis. If the synthesis of the new muscle protein is greater than the breakdown of the protein then muscle gains will be seen.
Casein on the other hand takes up to 3-4 hours or more to see the peak in Amino Acids in your blood. It dramatically slows the rate of protein breakdown. So does this make it a weak contender against Whey? No.
Whey and Casein are both great, but suited for different times of the day. Casein taken just before bed gives your body a long time to slowly complete protein synthesis. Straight after a work out your body is craving proteins to help repair the muscles, and this is where Whey comes in with it’s quick hit. In between meals and at night the body does not need these, so this is an ideal time for the slower absorbing protein Casein to be taken. Instead of fasting the body and risking muscle catabolism (not providing necessary nutrients to build and rebuild muscle) overnight Casein slowly feeds proteins to the body over a period of hours.
These articles are written as guidelines. Care should be taken when using supplements, please consult a nutritionist or doctor.