Energy

Fats, carbohydrates and proteins give you energy.

The amount of energy needed to keep the heart beating and the body breathing is the basal metabolic rate (BMR)

Total energy needed = BMR+energy used to work, play etc.

If you eat more than your body needs, the extra energy is stored as adipose tissue (fat), and you gain weight.

This can lead to obesity, which is when someone has at least 20% more body fat then the norm for their height and build. This places a lot of strain and the heart and muscles.

If you eat less then you need, your body uses up the stores of adipose tissue, and you lose weight. Anorexia is a mental illness, when sufferers refuse to eat and therefore become dangerously thin. They often have a distorted image of themselves, thinking they need to lose weight.

There are 2 key ways to lose weight:

1. Eating a balanced diet

2. Get plenty of exercise