To say it simply, a calorie is a unit of energy. In nutrition and everyday language, calories refer to energy consumption through eating and drinking, and energy usage through physical activity. 

The human body needs calories to survive, without energy our cells would die, our hearts and lungs would stop, and we would perish. We acquire this energy from food and drink.

If we consume just the number of calories our body needs each day, every day, we will probably enjoy happy and healthy lives. If our calorie consumption is too low or too high, we will eventually experience health complications.

The number of calories food contains tells us how much potential energy they posses. For example, 1 gram of carbohydrates contains 4 calories, 1 gram of protein contains 4 calories and 1 gram of fat contains 9 calories. 

How many calories do we need each day?

Not everybody requires the same number of calories each day. Our ideal calorific consumption depends on several factors, including our overall general health, physical activity demands, sex, weight, height, and shape. A 6ft tall, 20-year-old college athlete requires many more calories per day than a 5ft tall sedentary, 75-year-old woman. 

It's difficult to determine how many calories each individual needs but the US government says the average man requires 2,700 calories per day and the average woman 2,200 calories per day. Click here to determine your personal daily calorific needs. 

Related article: Will Cutting Out Sugar Help You Lose Weight 

Related Article: The Simple Math Behind Weight Loss