A gram of something contains a number of protons and neutrons equal to a six followed by twenty-two zeroes. Usually, it carries about half that number of electrons as well. Each day, an adult human consumes about 500 grams to 1,000 grams of food, and 2,000 to 8,000 grams of water. Larger or more active people need more food and more water, and of course you need more water in a hot desert than in a cooler place. So, multiply the number of particles in a gram by 2,500 to 10,000, depending, and that's the number of particles that go in each day. If that matter went in and did not come out, then it would be added to the human's weight, so most of what goes in also comes out (people do gain weight, but not that fast).