Macronutrients Main food groups
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Measuring the Calories in the Three Types of Macronutrients

Measuring the Calories in the Three Types of Macronutrients

Everything we know about nutrition – from the amounts of calories in different macronutrients to calculating our BMR and daily caloric needs – is based on averages.

Different types of carbohydrates, for example, have very different “heats of combustion” or calories: monosaccharides (simple sugars) have 3.75 kcal/g; disaccharides have 3.95 kcal/g; and, polysaccharides (complex sugars) have between 4.15 – 4.2 kcal/g. When you average out these different types of carbs, you come up with approximately 4 kcal/g, which is the caloric value that is accepted in the U.S. and most of the world for all carbohydrates.

The same is true for different types of proteins and fats. By setting one numeric value for each category of macronutrients, Wilbur Olin Atwater managed to put a realistic value on proteins, carbohydrates and fats that allows us to control and track the amounts of energy we consume and expend. Despite controversy over the “Atwater System” it is still the most widely accepted system for measuring the caloric values of the three primary macronutrients.