Which macronutrient provides the most energy per gram?

Which macronutrient provides the most energy per gram?

• A. Fat
• B. Carbohydrates
• C. Protein
• D. Alcohol

Answer: (A)

Energy density varies by macronutrient, and fat provides the most energy per gram. Fat yields about 9 kcal per gram, while carbohydrates and proteins each yield about 4 kcal per gram. Alcohol isn’t a macronutrient, but it does contribute energy at about 7 kcal per gram. The high energy density of fat comes from its chemical structure—fats are highly reduced, so when they are oxidized in metabolism, more energy is released per gram than from carbs or protein. In practical terms, small amounts of fat carry more calories, which is why fats are the most energy-dense macronutrient.

Energy density varies by macronutrient, and fat provides the most energy per gram. Fat yields about 9 kcal per gram, while carbohydrates and proteins each yield about 4 kcal per gram. Alcohol isn’t a macronutrient, but it does contribute energy at about 7 kcal per gram. The high energy density of fat comes from its chemical structure—fats are highly reduced, so when they are oxidized in metabolism, more energy is released per gram than from carbs or protein. In practical terms, small amounts of fat carry more calories, which is why fats are the most energy-dense macronutrient.