If carbohydrates provide 4 kcal per gram, fats provide about how many kcal per gram?

• A. 9
• B. 8
• C. 4
• D. 6

Answer: (A)

Fats provide about 9 kcal per gram because they are more reduced and contain many carbon–hydrogen bonds, while carbohydrates are more oxidized and contain more oxygen. When fats are metabolized, more energy is released per unit mass than from carbohydrates, and stored fat has little associated water, making it more energy-dense. So fats yield roughly 9 kcal per gram.