This Product Contains No Energy!

Food Energy
is measured 

Average diet is equivalent to about
100 watts

Americans have, for the most part, been well fed for generations --- too well fed in some instances.  However, the American fetish for slim figures comes not so much from health considerations as from perceived beauty.  Hence, we have "diet" products on our grocers' shelves that say "NO CALORIES" or "ONLY ONE CALORIE."

The food calorie is a kilocalorie --- the heat that will raise the temperature of one kilogram of water one degree Celsius.  It is equal to 4186 joules.  A diet of 2400 calories per day, equal to 100 calories per hour, is equivalent to 116 joules per second, or 116 watts.

Most of the food calories are used in heat production or locomotion.  For example, a person who gains an incredible 50 kilograms (110 pounds) in a single year has converted about 1200 calories per day (about half of a normal dietary consumption) into fat, and such a person would normally be a very heavy eater.

But the energy of locomotion winds up as heat in the environment.  Therefore, in large buildings, an estimate of 100 watts of heat produced per person is considered part of the normal heating/air-conditioning calculations.

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