In general, foods are made up of carbohydrates, proteins, and fats, each of which provide a different number of calories: 1  Carbohydrates provide 4 calories per gram. 2  Proteins provide 4 calories per gram. 3  Fats provide 9 calories per gram.
You need water to digest your food and get rid of waste, too. Water is needed for digestive juices, urine (pee), and poop. And you can bet that water is the main ingredient in perspiration, also called sweat. Besides being an important part of the fluids in your body, water is needed by each cell to function normally. Your body doesn't get water only from drinking water. Any fluid you drink will contain water, but water and milk are the best choices. Lots of foods contain water, too.
Water is essential for proper digestion, nutrient absorption and chemical reactions. The carbohydrates and proteins that our bodies use as food are metabolized and transported by water in the bloodstream. No less important is the ability of water to transport waste material out of our bodies.