Asteroids range in size from Ceres-the largest at about 950 kilometers (590 miles) in diameter and also identified as a dwarf planet-to bodies that are less than 1 kilometer (0.6 mile) across. The total mass of all the asteroids combined is less than that of Earth's Moon.
Only about one-third of the protein eaten around the world comes from animals raised for food. Much of the protein consumed around the world comes from vegetarian sources, including grains, legumes, nuts and seeds. Three grains -- wheat, maize and rice -- provide 60 percent of the world's energy, as well as a good percentage of the protein consumed.
We get our energy from the nutrients in food. The main sources of energy are carbohydrates (starches and sugars), fats and proteins. The body can be compared to an engine that converts the energy in food into the energy we need to live. Sugars and starches are forms of carbohydrate.