One Elephant's Worth: How Much Stool Does a Human Produce in a Lifetime?
Over a lifetime, a human produces roughly 5,249 kg of stool — about the weight of an adult African elephant. We calculate what fraction of your daily calories exits unused, why a vegan diet scores 74% digestive efficiency while a low-fiber diet hits 93%, and what Kleiber's Law tells us about why mice produce more waste per kilogram than elephants.