A calorie is actually a unit of heat energy. We think of calories as a measurement of food and all foods have calories. But your body sees calories as energy and it’s energy to produce heat. In comparison, heat energy is what really fuels our body just the same way that gasoline is what fuels your car’s energy.
Now all foods have calories and different foods have different amounts of calories. Calories are provided by fat, carbohydrate, and protein.
Fats have the highest concentration of calories. That’s nine calories per gram of pure fat. Protein and carbohydrates each have four calories per gram of pure protein or pure carbohydrate. Alcohol, pure alcohol, has seven calories per gram. So understanding the role of calories in your diet can help you balance your calories in with your calories out, and help you achieve weight management goals.