Food Energy

Introduction

• Food serves as a source of energy that is passed from the food to the consumer.
• 'Food energy' is quantified in joules (J) or kilojoules (kJ).
• Various food types or groups contain differing energy levels.
• Energy requirements vary among individuals.

What is food energy?

• Food serves as a reservoir of chemical energy that gets passed on to the consumer-an organism, typically an animal or fungus, that acquires its energy by consuming other organisms.
• The stored energy in food is then transferred to the consuming animal, sustaining its vital functions and activities.
• Each individual's energy demands dictate the specific amount of food required for sustenance.
• This energy, sourced from both plants and animals, is pivotal in maintaining the consumer's life and enabling its daily functions.

How much energy do you need?

• Energy is quantified in joules (J) or kilojoules (kJ). A previous unit for measuring food energy is the kilocalorie, often referred to as calories, where one calorie equals 4.2 J.
• Various animals require different energy quantities. For instance, an elephant needs approximately 200,000 kJ daily, while a cat requires about 800 kJ.
• The energy requirements of a human vary based on factors such as age and activity level. An elite athlete who trains regularly would necessitate significantly more energy compared to an average individual. During pregnancy, additional energy is essential to support the growth of the unborn baby. For example, a 13-year-old girl typically needs 9,000 kJ each day, while a boy of the same age requires around 10,000 kJ daily.

Different food groups

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

• Fruit and vegetables: Proteins build healthy muscles and allow the body to grow and repair.
• Proteins: Fats and oils act as an energy store.
• Fats and oils: Carbohydrates keep energy levels up.
• Carbohydrates: Dairy contains calcium for strong teeth and bones.