What is a Calorie?

A Calorie is a unit of energy. It measures the potential energy stored in the chemical bonds in food. We extract this energy through digestion to perform our daily functions.

There are two main definitions of a calorie; a Calorie with an uppercase C and one with a lowercase c. They represent two different units of energy. A calorie with a lowercase c is used primarily in scientific applications. In contrast, a Calorie with an uppercase C, also known as a large calorie, is often used to measure the energy content of foods and drinks.

A large calorie equals 1,000 calories or 1 kilocalorie (kcal). When you see a food label that lists "Calories" (with a capital "C"), it refers to kilocalories or large Calories. One large calorie or kilocalorie equals the energy required to raise the temperature of one kilogram of water by one degree Celsius.

Our diets primarily get calories from three macronutrients: fats, carbohydrates, and proteins. Regarding energy density or Calories per gram, fats are the densest macronutrient. They contain 9 Calories per gram. Carbohydrates are less dense than fats, containing 4 Calories per gram. Proteins also measure in at 4 Calories per gram. Alcohol is also an energy source, measuring 7 Calories per gram.

You'll stay the same weight if you consume the same amount of calories your body utilizes daily. You'll gain weight if you consume more calories than you burn and lose weight if you consume fewer calories than your body burns.