Calorie Definition and Why We Count Them

Calories in Food

Different types of food provide different levels of energy. That is, the three macronutrients are not all equal in the number of calories they provide. Protein and carbohydrate have less than half of the calories per gram as fat does.

Macronutrient Calories per Gram:

  • Carbohydrate: 4 calories per gram

  • Fat: 9 calories per gram

  • Protein: 4 calories per gram