That something is probably carbohydrate. Your body's fuel Carbohydrates are the fuel your body needs to work. Your brain, for example, primarily uses a carbohydrate as its source of energy.
Most carbohydrates are plant-based.
Dairy products are the only animal-based foods with significant carbohydrates. Sugars and starches provide 4 calories per gram of carbohydrate. Fiber has no calorie value because it's not absorbed. Instead, it helps to move things more easily through your digestive system and can slow the absorption of calories. For comparison, fat has 9 calories per gram.