Final answer:
Calories are the units of energy that serve as fuel for the body to function, and are commonly used to measure the energy content in food. A calorie can be defined as the heat required to raise the temperature of 1 gram of water by 1°C.
Step-by-step explanation:
The units of energy that are the fuel for your body to function are called calories. A calorie (cal) is the quantity of heat required to raise the temperature of 1 gram of water by 1°C. The other unit of energy is the joule (J), which is the SI unit of energy. When it comes to energy contained within food, calories are commonly used. For instance, to raise the temperature of 100 g of water from 20°C to 22°C, it would require 200 calories (100 × 2 cal). Both calories and joules are standard measures of energy, with 1 calorie being equivalent to 4.184 joules.