6.2Unit 7: Nutrition, health and movement
A balanced diet — Cambridge Checkpoint Biology 0893 Revision Notes & Topical Questions
5 min read 10 parts Lesson 2 of 4 1 quiz
Lesson summary
6.2 A balanced diet — CHECKPOINT BIOLOGY 0893 notes: Explain what a balanced diet is, why different people need different diets, and why some nutrients should not be eaten in excess.Diet = the food that a person eats each day.Balanced diet = a diet that provides all the different…
- Malnutrition
- Constipation
- Balanced diet = a diet that provides all the different nutrients and the right amount of energy
- The energy in the food eaten each day should be about equal to the energy used
- Most energy comes from carbohydrates and fats
- Different people use different amounts of energy.People who do a lot of sport, walking or running use more energy
Part 1 of 8Balanced diet
Diet
Diet the food that a person eats each day.
Balanced diet
Balanced diet a diet that provides all the different nutrients and the right amount of energy.
The energy in the food eaten each day should be about equal to the energy used.
Most energy comes from carbohydrates and fats.
Part 2 of 8Energy needs
Energy needs
Different people use different amounts of energy.
- People who do a lot of sport, walking or running use more energy.
- People who do not move around much use less energy.
- Some people's genes make their bodies use energy more quickly.
- Someone who is growing fast needs extra energy to help cells divide.
- Tall people use more energy to move their bodies than small people.
Energy is measured in joules, and a megajoule is one million joules.
A man aged 50 needs less energy than a boy aged 15, and most 15-year-old girls need less than 15-year-old boys.
Part 3 of 8Different diets
1
Everyone needs plenty of minerals and vitamins, but people vary in how much protein and carbohydrate they need.
2
Young people who are growing need a lot of protein to make new cells.
- If they use a lot of energy, they need enough carbohydrate.
- They need a little fat for energy and for making cell membranes.
3
People who sit down for much of the day do not need as much carbohydrate or fat as active people.
4
A pregnant woman needs:
- Plenty of protein to build her baby's new cells.
- Lots of iron to make haemoglobin in her blood and her baby's blood.
- Plenty of calcium to build her baby's bones.
Part 4 of 8Fibre
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Fibre is not a nutrient, because it cannot be digested and so does not go into the blood or to cells.
2
It travels through the digestive system and leaves the body as faeces.
3
Fibre keeps the digestive system healthy by preventing constipation.
4
Fibre is mostly cellulose from plant cell walls.
5
Good sources are cereal grains, seeds and fresh fruit and vegetables, which also contain many minerals and vitamins.
Part 5 of 8Food groups
- A food triangle shows how much of each kind of food should be in the diet, and the bigger the area the larger the proportion.
| Food group | Proportion | Nutrients provided |
|---|---|---|
| Rice, bread and pasta, preferably whole grain | Plenty | Starch and fibre |
| Fresh fruit and vegetables | Lots | Minerals, vitamins and fibre |
| Meat, fish, eggs, pulses and dairy products | Quite a lot | Protein |
| Sweets and fried foods | Not too many | Sugar and fat |
Food groups
Whole-grain bread and brown rice are better than white bread or rice because they contain more fibre.
A person who does not eat meat or fish can get protein from eggs, pulses, dairy products and nuts.
Part 6 of 8Not too much
1
Too much sugar can make teeth decay and increases the risk of diabetes.
2
Too much fat, oil or carbohydrate makes people put on weight, which strains the joints, heart and other organs.
3
Eating too many fats from animals increases the risk of heart disease.
4
Eating more energy than is used leads to fat being stored and to obesity.
Part 7 of 8Malnutrition
Malnutrition
Malnutrition an unbalanced diet, with too much or too little of some nutrients.
Too little protein causes kwashiorkor, and too little food overall causes starvation.
Not eating enough food means cells, tissues and organs do not have enough energy to stay healthy.
Part 8 of 8Healthy eating advice
1
Eat a variety of foods so every nutrient, vitamin and mineral is included.
2
Eat fruit and vegetables for fibre and vitamins.
3
Avoid eating too much fatty food, because it often contains a lot of animal fat and few vitamins or minerals.
4
Do not skip meals or eat too little.
Key terms
| Term | Meaning |
|---|---|
| Diet | The food that a person eats each day. |
| Balanced diet | A diet that supplies all the nutrients and the right amount of energy. |
| Fibre | Mostly cellulose from plants that cannot be digested but keeps the digestive system healthy. |
| Constipation | A slow-down of the digestive system so that faeces collect inside it. |
| Malnutrition | An unbalanced diet with too much or too little of some nutrients. |
| Megajoule | One million joules, a unit used for energy needs. |
Avoid these mistakes
1
Saying a balanced diet means eating equal amounts of every food — it means the right amounts of each nutrient and enough energy.
2
Saying everyone needs the same diet — energy and protein needs depend on age, activity and growth.
3
Saying fibre is digested — it is not digested and leaves as faeces.
4
Saying fat and sugar are bad in any amount — they are needed, but not too much.
5
Saying a diet with enough energy is automatically balanced — it must also contain all nutrients.
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