1. Energy and diet Learning objective:
Describe the right balance of energy and different foods required for good health.

2. Balanced diet
A balanced diet contains the different nutrients (e.g. carbohydrates, proteins, fats) in the correct amounts to keep us healthy. Imbalanced diets can cause obesity (overweight), starvation (underweight) and deficiency (not enough good things) diseases.

3. Energy needs
Each person needs a different amount of energy depending on factors such as:
gender (male or female)
Age
amount of daily activity
Job

4. Energy needs - how do we measure energy?
If you look on the side of food packets you will see the food's energy content. This is usually measured in kilojoules, kJ.
For example, a one-year-old baby needs 3850 kJ each day to continue to grow, whereas an adult Olympic swimmer in training needs 15,600 kJ each day.
3850 kJ kJ
Someone who sits at a desk all day will need less food than their twin who climbs ladders all day to wash windows.

5. Too thin, too fat
If the amount of energy you get from your food is different from the amount of energy you need, your diet will be imbalanced:
too little food may lead to a person being underweight too much food may lead to a person being overweight

6. What is a healthy height and weight?
For a given height, there is a range of body weight that is thought to be healthy.
A weight against height chart for men and women aged 18 and over

7. Energy calculations Food Energy Baked beans 1395 kJ per can Bread
The average man needs about 10,470 kJ per day, and the average woman needs about 8370 kJ per day.
Food labels show how much energy the food provides. The table shows three examples:
Using these numbers, the daily energy needs for a woman could be met from 6 cans of baked beans (8370 ÷ 1395 = 6) or from 23 slices of bread (8370 ÷ 364 = 23). The daily energy needs for a man could be met from 600 g of cheese (10470 ÷ = 600).
However, we need to eat a mixture of different foods in the correct proportions to achieve a balanced diet. The amount we need to eat will vary from person to person.
Food
Energy
Baked beans
1395 kJ per can
Bread
364 kJ per slice
Grated cheese
17.45 kJ per g