Carbohydrates are your body's main source of energy. Carbohydrates contain the simple sugar glucose, which supplies energy to your brain, muscles and nervous system. Carbohydrates are referred to as macronutrients for two reasons: your body needs them in large amounts and they provide calories -- 4 per gram.
Fats provide you with fatty acids, which are essential to your health. Fats also allow you to absorb certain vitamins, called fat-soluble vitamins, cushion your organs, help maintain your body temperature and insulate you. Like carbohydrates, fats are referred to as macronutrients. They are actually the densest macronutrient, providing 9 calories per gram. Fats can provide your body with energy.
Protein has more independent functions than any of the other nutrients. Proteins provide structural support to your body, help maintain acid-base balance, allow your body to build hormones and enzymes, transport various substances throughout your body and allow your immune system to function properly. Because proteins are also macronutrients and contain 4 calories per gram, they supply your body with energy in the absence of carbohydrates and fats.
Vitamins are organic compounds, which means plants or animals make them. Vitamins are considered micronutrients because your body only needs them in small amounts. Each vitamin has an independent function, but vitamins are grouped together because all of them allow chemical reactions to take place in your body. Vitamins are divided into two categories based on how your body absorbs them -- fat-soluble and water-soluble. The fat-soluble vitamins include vitamins A, D, E and K and the water-soluble vitamins are vitamin C and the B vitamins.
Minerals are considered inorganic compounds because they come from soil and water, rather than living things. Minerals help regulate body functions and allow your tissues to grow. Minerals also play a role in the release of energy in...