How many calories are in one gram of carbohydrate?

• A. 3.75 kcal
• B. 4 kcal
• C. 9 kcal
• D. 2 kcal

Answer: (A)

Carbohydrates provide energy when they are metabolized, and that energy value is about 15.7 kilojoules per gram. Converting to kilocalories using 1 kilocalorie equals 4.184 kilojoules gives 15.7 kJ ÷ 4.184 kJ/kcal ≈ 3.75 kcal per gram. In this course's context, the precise figure used for carbohydrate is 3.75 kcal per gram, which is why that option is the best choice. The other numbers don’t fit: 9 kcal per gram is the energy value typically associated with fat, and values around 2 kcal or 4 kcal per gram are either too low or represent a rounded approximation rather than the precise figure used here.