Protein contains nitrogen and provides amino acids that are essential for building body proteins. Protein is used to build muscle and maintain/repair lean tissue, including muscle and body organs.
There are nine essential amino acids: histidine (essential for children), isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. These amino acids must be supplied by food; the body cannot make them. There are also 12 nonessential amino acids, which are important, but called nonessential because the body can make them from the essential amino acids. Proteins come from plant and animal sources. Animal proteins more closely match the amino acid composition of human proteins, however people who do not consume animal foods can get all of the protein needs from plant sources, they just require need a larger amount of plant protein versus animal protein to fulfill the body's requirement for protein. "According to the Food and Nutrition Board of the National Research Council (who establish dietary recommendations for the population), the body's need for protein is met when protein intake is at 0.8 grams of protein per kilogram of body weight."(www.weightloss.com) Thus, men need approximately 63 grams of protein per day, and for women, it is about 50 grams of protein per day. In the past few years, there has been a swing towards hatred of carbohydrates, and carbohydrates are being blamed for the obesity problem. The option on protein diets is to increase fat and/or protein in the diet to make up for a low-carbohydrate intake. This is the wrong approch because with high protein, high fat diets it severely limit sources of carbohydrates that provide essential vitamins, minerals and other protective factors against serious diseases such as cancer, heart disease, and high blood pressure. There is also the factor that at very low levels of carbohydrate intake, the body produces ketones, which is a potentially dangerous condition.
