Despite their immense importance, the body has no mechanism to store amino acids. This stems form the fact that they contain some nitrogen compounds which if left to accumulate may become toxic. This is made worse by the acidic nature of protein which may topple the pH balance of the internal body environment. Thus excess amino acids are oxidized in the liver where their carbon content is striped off to be used for energy and the rest is converted to a highly soluble compound called urea which is dissolved in water to form urine. This is largely how surplus amino acids are discarded from the body.
Thus complete proteins must be included in every meal to replenish the amount available for muscle growth. This sheds light on the average body builder's fixation with protein-fused meals six times a day. A great source of these complete proteins includes meat, eggs, milk, beans, legumes and grains. Some lack one essential amino acids or another so it's advised to take them in combination to supplement their amino acid content.
Unfortunately for our vegetarian friends, while you can be fit and healthy on a vegan diet, it is not likely to get you the Mr. Universe title. This is because you need some eggs or dairy products for that magical touch they seem to add. Combining a vegetarian diet and some eggs and milk products will definitely get you there as they contain all the essential amino acids necessary for muscle growth. These are animal products which are an aversion to vegetarians. So of you are a vegetarian seeking the title, you will have to forego one for the other. The economists term for this is opportunity cost.
For the meat loving body builder, not all meat is good. Animal meat is rife with saturated fats that are unwanted. Opt for lean cuts such as egg whites instead of egg yolk, turkey and chicken breast and non fat dairy products instead of whole milk. As a rule of thumb, go for white meat and avoid red meat. You will reduce the amount of bad fats ingested while keeping you sufficiently nourished with the good kinds of amino acids.
What is the amount of protein that is right for me? You may ask. Well according to Recommended Daily Allowance, a set of nutritional guidelines establish by the national research council of the US, you should take 0.36 grams per pound of your body weight. However, among bodybuilders the rule of thumb is i1 gram of complete protein per pound of body weight is adequate. Since this is from the horse's mouth it is best to take it as the gospel truth.
In conclusion, to stay fit and possibly grow some muscles, an average meal consisting of 55% carbohydrates, 30% protein and 15% fat is advised. This is healthy and balanced to supply all your body needs. This is merely a guide though. The optimal diet balance varies from person to person depending on how intense you are training and even your actual goal in training, be it to lose weight or gain muscles.