Eli5 how are calories measured in food

Question

Eli5 how are calories measured in food

In: 23

Answer 1

Basically we know the calorie(available chemical energy) of the macro nutrients, fiber sugars carbohydrates, fats proteins etc.

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And then we measure how much of each of those is in an item to sum up the total caloric value. For instance in chemistry you might try to dissolve the fat of something and measure how much the weight difference is, that way you estimate how much fat there was in the item.

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These are estimates though and can be quite a bit off.