Balanced Diet (Food Groups) Lesson | GCSE Biology Edexcel IGCSE Triple

Balanced Diet (Food Groups)

This lesson covers:

What the different biological molecules (nutrients) are, including carbohydrates, lipids, proteins, vitamins, mineral ions, fibre and water.
Which foods each biological molecule is found in
Why we need each type of biological molecule

Illustration of a basket containing healthy foods including vegetables, cheese, and fruits.

Balanced Diet

A balanced diet is a diet that includes appropriate proportions of all the different biological molecules, including carbohydrates, proteins, lipids, vitamins, minerals, dietary fibre, and water.

Too much or too little of any of these could lead to problems. For example, too much food in general could lead to obesity, but a lack of any particular one could lead to a deficiency disease such as scurvy.

Illustration showing blueberries, cheese, and an apple as sources of energy.

How much energy do we need?

We get energy from the food we eat. Although carbohydrates are our main source of energy, lipids are also used for energy, and even proteins can be broken down for energy if necessary.

As in physics, we can measure energy in Joules (J). However, in the case of food, we often use calories instead.

Illustration showing the energy content of an apple with 502 kJ and 120 kcal.

How much energy we need each day depends on a lot of things, but there are 3 main factors to consider:

Activity level - The more active you are, e.g. if you're an athlete, the more energy you need.
Age - Teenagers often need a lot of energy because they're growing, whereas elderly people need less.
Pregnancy - Pregnant women need more energy because the baby growing inside them requires a lot of energy.

Which 3 of the biological molecules below do we need in large quantities?

(Select all that apply)

Carbohydrates

Lipids

Vitamins

Minerals

Proteins

Diagram showing the molecular structure of a carbohydrate.

Why do we need carbohydrates?

To provide energy for chemical reactions

To help food move through our intestines

To repair damaged tissue

To insulate us and regulate our body temperature

Fats and oils together make the food group known as:

Lipids

Why do we need lipids?

(Select 2 options from the list below)

To help food move through our intestines

To provide energy for chemical reactions

To insulate us and regulate our body temperature

To repair damaged tissue

lipids / carbohydrates / proteins

Starchy foods like potatoes, bread, and pasta contain a lot of .
Meat, fish, and legumes contain a lot of .
Cheese, nuts, and avocados contain a lot of .

carbohydrates

proteins

lipids

Illustration showing various food groups in a basket and their role in producing new cells.

Which food group is the most important for growth and producing new cells?

Carbohydrates

Lipids

Proteins

Mineral ions

Which vitamin or mineral ion is important for good vision and healthy hair and skin?

Vitamin C

Calcium

Iron

Vitamin D

Vitamin A

Illustration of a bone representing the importance of minerals for strong bones.

Which mineral is important for strong bones?

Calcium

Illustration of vitamin C deficiency with vitamin C tablets.

Which disease can be caused by lack of vitamin C?

Scurvy

Illustration showing the importance of iron in the diet with a focus on iron-rich vegetables.

Explain why it is important that we get enough iron in our diet.

Why do we need fibre?

To provide energy for chemical reactions

To reduce the risk of dehydration

To help food move through our intestines

To prevent us from getting rickets

Illustration of a water droplet with a blue outline.

What are the 3 main ways by which we lose water from the body?

Illustration of a person cycling in sunlight to represent vitamin D absorption.

Which vitamin or mineral ion helps us to absorb calcium, and can be made by the body, using sunlight?

Iron

Vitamin C

Calcium

Vitamin A

Vitamin D