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. All foods are sources of energy; however, protein provides a greater boost in energy levels since it is absorbed slowly and thus produces a constant source of energy. Protein has real energy-staying power for your active, healthy, lifestyle. Fats and carbohydrates produce quick bursts of energy but cannot be relied upon to provide the body with a continuous source of energy, since they are digested and metabolized more quickly than protein. Fats and carbohydrates also tend to be stored as fat the body for later use. The Protein that we're discussing is lean protein (lean meats, skinless poultry, seafood, egg whites, low-fat dairy products, legumes and beans, soy and tofu foods, skim and low- fat cheeses, and good-fat nuts). Lean proteins are also excellent sources of selenium, which. Is a mineral that protects the body against dangerous tree radicals that can destroy normal cells in the body. These free radicals can damage many different types of cells including connective tissue, which causes joint and muscle inflammation. High-saturated fat protein products like fatty meats, hard cheeses, whole fat milk dairy products, whole eggs, mayonnaise, luncheon and smoked meats including bacon, sausage, and hot dogs are definitely not good sources of energy production. The reason for this is, that even though these products have some protein content, its value is offset by the saturated fat content of these foods. The saturated fat content of these foods do more harm to the body (heart disease, strokes, hypertension, high cholesterol and some forms of cancer) than the protein portion of the food can repair. These are called harmful proteins and are not recommended for any healthful weight-loss program. For appetite control, lean protein tops the charts for staying power. By adding a small portion of lean protein to your meal, you'll control hunger pangs for hours. Lean protein also has the advantage of being lower in calories than many foods, particularly saturated fat protein product refined carbohydrates and saturated fat foods. Once you substitute saturated-fat protein products, you defeat the appetite-controlling factor of the protein. The fat content of saturated- fat protein foods prevents the brain's appetite-control center from shutting down. In other words, you'll get hungry soon after your meal of a saturated protein food. Your body needs between 15-30 of your total daily calories, however, can be dangerous, because it strains the kidneys. This is one of the reasons among many why low-carbohydrate, high saturated fat protein diets are dangerous to your health.