The calories produced by 1 gram of fat is 9 kcal, and the calories produced by 100 grams of fat are calculated by multiplying 100 grams by 9 kcal per gram equals 900 kcal, which is 900 kcal for the human body equivalent to walking for a long time before it can be consumed. So the energy density of fat is actually the highest, generating 9 kcal per gram. In addition to ethanol, alcohol produces 7 kcal per gram, and protein and carbohydrates produce 4 kcal per gram, so fat has the highest caloric and energy density, with 9 kcal per gram of fat, and 900 kcal per 100 grams of fat.