Food energy

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Key points

  • Food is a store of energy, transferred from the food to the consumer.
  • 'Food energy' is measured in joules (J) or kilojoules (kJ.)
  • Food types (groups) have different amounts of energy.
  • Different people need different amounts of energy.

What is food energy?

  • Food is a store of chemical energy, which is transferred to the when eaten.
  • Stored energy from the food is transferred to the animal that eats it (the consumer).
  • Each individual requires a specific amount of food, depending on their energy requirements.
  • This energy from plants and animals keeps the consumer alive and allows it to carry out its activities.

Video - sports nutritionist

Watch to find out more about food energy and different food groups.

Learn about food energy from a sports nutritionist

Sports nutritionists guide athletes in deciding what to eat to perform at their best. They need a good knowledge of how much energy is stored in different foods, as well as understanding how quickly the energy is released to the body.

How much energy do you need?

  • Energy is measured in joules (J) or kilojoules (kJ). An older unit for measuring food energy is the kilocalorie, often just called calories. One calorie is 4.2 J.
  • Different animals need different amounts of energy. An elephant needs around 200,000 kJ every day, and a cat about 800 kJ.
  • The amount of energy a human needs depends on many things, including their age and what they are doing. An elite athlete training regularly would need much more energy than the average person. During pregnancy more energy is required to help the unborn baby grow.
  • Typically, a 13-year-old girl would need 9,000 kJ every day and a 13-year-old boy would need around 10,000 kJ every day.

Different food groups

examples of fruit and vegetables, protien, fats and oils, carbohydrates and dairy on one big plate.
The food groups

Each one of the five food groups is important. All food contains energy.

  1. Fruit and vegetables contain vitamins to keep the body working and help the immune system and fibre which helps digestion.
  2. Proteins build healthy muscles and allow the body to grow and repair.
  3. Fats and oils act as an energy store.
  4. Carbohydrates keep energy levels up.
  5. Dairy contains calcium for strong teeth and bones.

Video - jelly baby experiment

How much energy is in a jelly baby?

Everyone needs some knowledge of food energy, so that they can eat sensible amounts of the foods they need to stay healthy. Regularly consuming food containing more energy than you need can lead to becoming overweight and then .

Test your knowledge

Order the activities

Quiz - Food Energy