8. Health nuts

One way is to measure the amount of thermal energy produced when the food is completely combusted into carbon dioxide and water in a device called a bomb calorimeter. To avoid overestimating the actual calories available from food, bomb calorimetry measurements of fecal matter must be subtracted from those of the food.

This method is sometimes used for animal feed, but it is not very popular because bomb calorimeters are pricy. Plus, it is kind of a drag for researchers to have to follow people around with baggies to determine the caloric content of what passes through ...

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