Protein is found in all of your body’s cells. It is the essential nutrient that is responsible for the maintenance and repair of all of your organs, tissues, muscles, brain and bones. This individual built in repair kit occurs at the cellular level in our bodies. Protein regulates everything – our blood circulation, our metabolism and our immune system. Individuals who lack sufficient protein in their bodies have weaker immune systems than people who consume adequate protein in their diets. Also, people who are constantly on yo-yo diets where they lose and gain weight back frequently usually become protein deficient and have weaker immune systems. This fact has been proven by researchers who have found that these yo-yo dieters have about a third lower the number of killer cell activity than normal individuals. The so-called killer blood cells are essential for the immune system to function properly.