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.
While much of the protein in the American diet comes from beef and pork, this isn't necessarily the case around the world. People in some countries eat little or no meat, getting much of their protein from vegetarian protein sources, and some people get their protein from foods many Americans have never tried.
Daily nutrition comes from three main sources: carbohydrates, proteins and fats. Carbohydrates are the main source of energy for muscles and the brain; protein provides the building blocks for new muscle and tissue cells; and fat plays a key role in nerve and brain function as well as regulating hormones in the body.