03 Apt 2013 Dietary fat is one of the three macronutrients (fats, carbohydrates and proteins) the body uses for energy. It is the most energy dense of the macronutrients, providing 9 calories per gram (compared to 4 calories per gram for carbs and proteins). Contrary to the popular belief that eating fat makes you fat, fat has many important functions within the body. Attempting to eliminate fat from the diet leads to serious health consequences.