# What exactly is a calorie?

Asked by

JimmyMac (

2)
February 27th, 2008
from iPhone

I know if I consume lots, I’ll get fat. But what is a calorie?

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## 3 Answers

A calorie is technically defined as the amount of energy it takes to heat 1 cubic centimeter of water by one degree Celsius. It’s a basic energy measure. You’re body can only burn off so much by doing different things, so if you take in more energy than you burn… your body stores the extra as fat.

What abrushing said. A calorie is basically a unit of energy. There are 3500 of them in a pound of fat. (Fat is a really effective energy storage system!)

one small adjustment – there are two kinds of calories (confusing, right?) There’s a strictly physics calorie which is what abrushing said—the amount of energy required to heat 1 cc of water by 1 degree Celsius.

But a nutritional Calorie is a bit different! That’s 1000 physics calories. So it’s the energy required to heat 1000 cubic centimeters (a metric litre) of water 1 degree Celsius (or 1 cc of water by 1000 degrees Celsius). So, if there are 120 (dietary) Calories in a tablespoon of olive oil, theoretically you could burn that olive oil and heat a litre of water by 120 degrees Celsius (unfortunately, we can’t be totally efficient, so the water doesn’t end up heating up nearly that much).

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