Calories

A calorie is a unit of heat energy. Anything that contains energy contains calories. Everything from apples to running to coal can be measured in caloric potential, consumption, or usage. However, the word “calorie” in everyday language refers to energy consumption through eating and drinking and energy usage through exercise and the basic functions of our organs and tissues. You should aim to get the majority of your calories from nutrient-dense foods. Here is a wonderful TED-Ed video overview that explains calories:

Interesting side note: The word “calories” that you will find on any nutrition label is slightly misleading. Scientifically speaking, a calorie is the amount of energy required to raise one gram of water by one degree Celsius (from 14.5 to 15.5 degrees Celsius). But the “calories” listed on food nutrition labels are actually kilocalories (the word “kilo” means “one thousand”), which, as the prefix kilo implies, possess 1,000 times the energy potential of a single calorie. Thus, a 100 “calorie” (kilocalorie or kcal) apple possesses enough energy to heat 100,000 grams (equivalent to 100 kilograms or approximately 220 pounds) of water by one degree Celsius. A little geeky and maybe unnecessary, but I won’t argue the point too much.