What is whey protein, is it the best for muscle building?

Question
I was wondering where whey protein comes from? Is it animal or plant? And is it best for rebuilding after a workout, or is there something better?

Answer
James,

The major types of proteins are from egg, whey, soy, and casein. The only 2 types used for muscle building (and rebuilding) are whey and casein.

Whey is an animal product so whey protein is an a protein of animal origin. It is the liquid part of milk in the cheese-making process. Casein, on the other hand, is the solid part of the same process and accounts for 80% of proteins in milk

The best way to use them is taking them together because they act differently.

Whey increases protein synthesis and casein blocks protein breakdown, a combination of both is optimal though the time table is different: whey is quickly absorbed and is best used during 45 minutes after workout. Casein protein is taken throughout the day, up to the bed time.

Q&A About Whey Protein
http://atkinszone.com/faq/2007/05/q-about-whey-protein.html

Protein Supplements Vs. Protein Foods?

http://atkinszone.com/fat_loss/2006/12/supplements-or-foods.html  

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