GCSE PE Revision - Energy and Exercise

The following nutrients can all be used for energy:

The energy value of all foods are measured in either Kilojoules (KJ) or Kilocalories (Kcal - usually just called calories!). The amount of energy we need every day depends on a number of factors:

BMR - Basal Metabolic Rate - this is the amount of energy our bodies need just to stay alive
Lifestyle - Those with a job involving sitting down won't need as much energy as those who move about all day
Exercise - If you exercise regularly you will need more calories
Age - Growing children and teenagers need more food than most adults!
Size - The bigger you are the more food you will need
Sex - Men usually need more food than women (even if they are the same size)

Altogether, the amount of food you need can be shown by this equation:

Total energy = BMR + Energy needs for work/sport etc

Weight Management

Eating too much or too little can have serious effects on your health and fitness. If you eat too much your body stores this as adipose tissue (fat) and you put on weight. The more weight you put on the more strain is placed on the heart, lungs, muscles and joints.

Loosing weight can be difficult for people who are overweight. There are two key factors to get right if you are trying to lose weight:

Eat a balanced diet, making sure you don't eat more calories than you are using per day. Also try to make sure your diet is not high in fat
Exercise more regularly. Not only will this burn calories at the time, but regular exercisers have a faster metabolism (BMR) than sedentary people. This means that even when your are resting you will use more calories!

If you don't consume as much energy as you are using, your body uses some of the stored adipose tissue for energy and you lose weight. This only becomes a problem if your amount of stored body fat drops dangerously low. This is what happens when someone suffers from anorexia. This is a mental illness in which the person believes they are larger than they are and refuse to eat much, or at all.

Body fat percentage (or body composition) is a good way of assessing if someone is at a healthy weight for them. This measures the amount of your body weight which is fat. Other methods such as weight or BMI (body mass index) don't take into account the height, build and muscle content (which is heavier than fat!) of the individual which can be inaccurate. For example, based on weight or BMI, over half of the England rugby team are obese!

Food energy