A calorie is a unit of energy. In nutrition, calories refer to the energy people obtain from the food and drinks they consume and the energy they expend through bodily processes and activity. There are two related definitions commonly used:
- Small calorie (cal): the amount of energy required to raise the temperature of 1 gram of water by 1 degree Celsius at one atmosphere of pressure.
- Large calorie (kcal), also called a kilocalorie or Calorie with a capital C: equal to 1,000 small calories. In dietary contexts, when nutrition labels say "calories," they are typically referring to kilocalories.
Key nuances:
- The kilocalorie (Calorie) is the energy value typically listed on food packaging and used in dietary planning.
- In scientific contexts, energy may be expressed in joules (1 calorie ≈ 4.184 joules; 1 kilocalorie ≈ 4,184 joules).
If you’d like, I can tailor this to a specific audience (students, nutrition planning, fitness) or provide examples comparing common foods.
