Six Basic NutrientsYou may know the six basic nutrients, but a refresher will be useful as we proceed through the chapter.▶▶ Carbohydrate. Carbohydrate, in the form of starch and sugar, provides energy for the muscles in the form of glycogen. The fiber in these foods helps digestion and the control of fat and cholesterol.▶▶ Protein. Protein is essential for developing new tissue and maintaining existing tissue, including muscles, red blood cells, and hair. The body needs protein to produce essential enzymes, antibodies, and hormones. Protein also helps control thewater level inside and outside the cells.▶▶ Fat. Fat is a primary source of stored energy that is used when the body is resting or engaged in long-term aerobic activity. Fat from animals (meat, butter) tends to be saturated and contributes to cardiovascular disease and cancer. Fat from plants (corn oil, canola oil, olive oil) is unsaturated and generally much healthier, but avoid trans fat, also called partially hydrogenated oil, which is vegetable fat processed to make it more solid. This type of fat contributes to heart disease and diabetes.