A calorie is a unit of food energy. 1 calorie = 4.2 kilojoules. This unit of measurement allows us to talk about how much energy a food contains and how much energy is used for our bodies to function and burned up during exercise.
How much energy there is in food is determined by how much carbohydrates, fats and protein there is in it! Fats and alcohol are the most energy dense food.
1g fat = 9 cal
1g alcohol = 7 cal
1g carbohydrate = 4 cal
1g protein = 4 cal
When we regularly eat more energy than our body needs, the excess is stored inside fat cells. Obviously if we eat less energy than we need -- we lose fat cells!! To lose 1kg in a week a person needs their energy balance to be 7000 cal in debit. How many calories a person uses per day depends on their age, gender, body composition, and activity levels.
Couple of interesting facts!
You burn more calories sleeping than you do watching TV.
The average deep fried mars bar contains almost 1,000 calories – that could be most of your daily allowance, if you’re a small female.