Unlike other nutrients in which most people are chronically deficient, most North Americans get plenty of proteins through their diet; it is thus unnecessary for them to supplement their diet with external, supplemental sources of protein. Proteins are found in all meats and in many vegetables and legumes, in various concentrations. Proteins are composed of a variety of amino acids, depending on their source. Complete proteins will contain all nine essential amino acids, and incomplete proteins will only contain some of them. Essential amino acids are elements that must be ingested through food or supplements, as the body can not synthesize them. Meat usually contains complete proteins, but is rich in fat and cholesterol, while legumes such as beans or rice will contain incomplete proteins, but in greater concentrations and with less fat.
Protein requirements will vary depending on your physique, physical shape and level of physical activity. Sedentary people, or with very low levels of physical activity, should not need more than 0.8 to 1.2 grams of protein per kilogram of weight, per day. Factors that can affect this basic requirement include pregnancy as well as recovery from an illness, or from surgery, where amino acids are required in greater quantity to build or repair cells.
Endurance athletes, as well as bodybuilders in maintenance mode, will require between 1.2 to 1.8 grams of protein per kilogram of body weight per day. Ideally, there should be enough amino acids present in the skeletal muscle cells to prevent protein catabolism, or the use of protein as a fuel source. Proteins and their amino acid components are not normally meant as fuel, but rather as structural building blocks, but will be used as such if not enough energy is present. Casein protein powder can be used as a supplement, as it promotes fat loss and will thus help prevent fat accumulation.
Bodybuilders who are in a training phase, and where the goal is to gain as much lean muscle mass as possible will benefit from maximal skeletal muscle cell amino acid saturation, and will need up to 3.6 grams of complete protein per kilogram of bodyweight per day. Studies have shown than more than twice the recommended maximum (which is 1.8 grams for athletes) will not yield greater results. To get that much complete protein, a bodybuilder would need to eat up to 1.8 kilograms of meat per day (a little under 4 pounds) which would be much too rich in fat and cholesterol. Bodybuilders can reach their target protein intake using whey isolate, a concentrated cheese manufacturing byproduct sold and used as a protein supplement.
It is recommended that you should get from 10% to 35% of your total caloric intake from protein. A target of 15% is appropriate for most people; bodybuilders and athlete, however, will trend towards 35%, depending on their weight, total caloric intake and current goals. Bodybuilders currently gaining muscle will need the most calories in their diet. Protein supplements can be used to make up the difference; they should never, however, be used as replacement. A healthy, balanced diet rich in fruits, vegetables and lean cuts of meat is an essential and unavoidable starting point that if done right, will help minimize the need for supplementation.
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