Calories from Fat
Energy from fat at 9 kcal per gram — the most energy-dense macronutrient.
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Example
10 g ⇒ 90 kcal
How it works
Fat provides about 9 kilocalories of energy for every gram because of its chemical structure: fat molecules contain many high-energy bonds and relatively little oxygen, so the body can release more energy from them than from carbohydrates or protein. This formula converts a mass of fat into its energy contribution in a food or diet calculation. It is a simple nutrition shortcut used on labels and in meal planning.
When to use it
Use this when you know how many grams of fat are in a food and want to estimate how many calories that fat contributes. It is helpful in nutrition labels, diet tracking, and comparing the energy density of foods.
Worked example, step by step
A snack contains 18 g of fat. Use the formula: E_F = 9F Substitute the value: E_F = 9 × 18 Calculate: E_F = 162 Final answer: the fat contributes 162 kcal
Common mistakes to avoid
- Using 9 calories instead of 9 kilocalories per gram
- Confusing grams of fat with total calories in the whole food
- Applying the formula to protein or carbohydrate instead of fat
Did You Know?
Fat packs more than twice the calories of protein or carbs, which is why a spoon of oil adds up so fast.
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