Mateo asks his doctor about calories. He wants to know how scientists determine that chips have 140 calories and an apple has 80 calories. How can the doctor BEST explain how this is calculated?

A food Calorie is a measure of energy, defined by the heat needed to raise the temperature of water. Scientists can determine a food’s energy content by measuring the heat released when it is burned in a calorimeter. So the best explanation is that calories are calculated based on the heat required to raise water’s temperature, not on weight gain or a ratio of nutrients.

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