A calorie is a unit of energy. We tend to associate calories
with food, but they apply to anything containing energy. Specifically, a calorie is the amount of energy, or heat, it
takes to raise the temperature of 1 gram of water by 1 degree Celsius (1.8
degrees Fahrenheit).
Most of us think of calories in relation to things we eat
and drink, as in "This can of soda has 200 calories." It turns out
that the calories listed on a food package are actually kilocalories (1000
calories = 1 kilocalorie). So that can of soda actually has 200,000 calories, but don't worry, the same applies to exercise when an exercise chart say
you burn 100 calories jogging a mile, it means 100,000 calories.
A food
"calorie" is sometimes capitalized to show the difference, but
usually not. Human beings need energy to survive -- to breathe, move,
pump blood -- and they acquire this energy from food. The number of calories in
a food is a measure of how much potential energy that food possesses.
Foods are a compilation of these three building blocks. So if you know how many carbohydrates, fats and proteins are in any given food, you know how many calories, or how much energy, that food contains.
- A gram of carbohydrates has 4 calories
- A gram of protein has 4 calories
- A gram of fat has 9 calories.
Foods are a compilation of these three building blocks. So if you know how many carbohydrates, fats and proteins are in any given food, you know how many calories, or how much energy, that food contains.
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