Protein

Protein is made of amino acids. Amino acids are the basic building blocks of muscle. Therefore, protein is an essential ingredient for muscle building. You can't build muscle without it! You will want to take in about 1-2 grams of protein per pound of bodyweight throughout the day.

There are several forms of protein including: Whey, Soy, Egg, and Casein. So which kind is best? Well that depends on how and when you want to use them.

Whey - Basically, whey protein is awesome for post-workout supplementation because that's the time when your body needs protein the most, and whey is digested very quickly (about 30 minutes).
Casein - Casein, on the other hand, is digested very slowly (over 2 - 7 hours). This means it's great to use a protein supplement with casein before bed because the longest time your body goes without protein is during the night while you are sleeping.
Egg - Egg protein (albumen) digests at a medium pace (1.5-3 hours) so it's a good anytime protein to provide a good sustained release of aminos to the body.
Soy - Soy protein is the vegetarian's friend because it's one of the only complete protein sources derived from plants. Soy is a good overall protein, although it's not as effective in terms of absorbtion as whey or egg albumen. Additionally, soy has many recognized health benefits for women.