What is a calorie?
the energy it takes to raise the temperature of 1 gram of water 1 degree Celsius
The first law of thermodynamics (the conservation of energy
matter can neither be created nor destroyed, so energy must be transferred from one system to another (in various forms)
If you have too much energy in your body, you will grow larger. If you have too little energy in your body, you will get smaller.
USDA Dietary Guidelines
say to balance calories
often blamed on a "toxic environment" in the U.S.