Fuel, Bricks and Shields: What a Balanced Diet Does for a Growing Body – Diet and Health (Senior 3 English) | Ganzaa

Diet and Health

Lessons

Senior 3 · English

Diet and Health

5 lessons

Lesson 1 of 5

Fuel, Bricks and Shields: What a Balanced Diet Does for a Growing Body

25 min

Let's begin

In S1 you sorted foods into groups. In S3 the question is harder: why does the body need each group, and what happens when it gets too little, or too much? The article below answers with three pictures that are easy to remember: fuel, bricks and shields. Read it as an informative text: look for the main idea of each paragraph and the facts that support it.

Before you read

What did you eat yesterday? Which meal kept you full the longest?
Can a person be badly nourished and overweight at the same time? Guess, then check in paragraph 5.

Reading: Fuel, Bricks and Shields

An article for a school health club magazine. The health facts follow the World Health Organization's fact sheet Healthy diet (updated 26 January 2026).

1 During adolescence your body grows faster than at any time since early childhood. Bones lengthen, muscles thicken, and the brain rewires itself for adult thinking. All of this is built from what you eat. A balanced diet is not a special diet for athletes or the sick: it is simply the right variety of foods, in the right amounts, for the body you are building.

2 Think first of fuel. Carbohydrates and fats give the body energy to walk to school, play football and concentrate in a three-hour examination. In Rwanda most of this fuel comes from staples such as sweet potatoes, cassava, maize, sorghum, rice and cooking bananas. The World Health Organization advises that carbohydrates should come mainly from whole grains, vegetables, fruits and pulses such as beans and peas, rather than from sugar. Fats matter too, but their quality counts: the fats in avocado, fish and sunflower oil are better choices than those in fatty meat, butter and palm oil.

3 Next come the bricks. Proteins build and repair every part of the body, from muscles to the enzymes that digest your lunch. Beans, peas, groundnuts and soya are cheap, rich sources, and so are milk, eggs, small dried fish and meat. A plate of beans eaten every day is one of the best habits a growing body can have.

4 Finally, the shields. Vitamins and minerals are needed in tiny amounts, yet without them the body cannot defend itself. Dark green leaves such as amaranth and cassava leaves, orange foods such as carrots and pumpkin, and fruits such as mangoes, oranges and passion fruit protect the eyes, the skin and the immune system. Iron, found in beans and dark green leaves, carries oxygen in the blood; too little of it causes anaemia, which leaves a student tired and unable to concentrate. Everyone older than ten should aim for at least 400 grams of fruit and vegetables a day, together with plenty of clean water and fibre.

5 When the balance tips, the result is malnutrition, and it can tip either way. Too little food, or too few nutrients over a long time, leads to stunting, anaemia and weak resistance to infection. Too much sugar, salt and unhealthy fat leads to overweight and obesity, type 2 diabetes, high blood pressure and heart disease. A person can even suffer from both at once: overweight, yet short of iron and vitamins. That is why the World Health Organization advises limiting free sugars to less than 10% of the day's energy, about 12 level teaspoons for an adult of healthy weight, and keeping salt for adults below 5 grams a day.

6 None of this requires expensive food. A meal of beans, a sweet potato, a handful of green leaves and a banana is balanced, local and affordable. The habits that matter most are simple: eat breakfast, eat a variety of colours, drink water instead of sweet drinks, and treat fried snacks and sweets as occasional, not daily, food.

Definition

Glossary

nutrient (n): a substance in food that the body needs to live and grow, such as protein, a vitamin or a mineral.
staple (n): a basic food eaten regularly that provides most of a people's energy, such as cassava, maize or rice.
pulses (n, plural): the dried seeds of plants such as beans, peas and lentils.
enzyme (n): a protein in the body that speeds up a chemical process, such as digesting food.
anaemia (n): a condition in which the blood cannot carry enough oxygen, often caused by too little iron. Adjective: anaemic.
malnutrition (n): poor health caused by eating too little, too much or the wrong kinds of food.
stunting (n): being too short for one's age because of poor nutrition and repeated illness over a long time, especially in early childhood.
fibre (n): the part of plant foods that the body cannot digest; it helps food pass through the gut. American spelling: fiber.
free sugars: sugars added to food and drinks, and the sugar in honey and fruit juice.

Malnutrition: a balance that tips both ways

Paragraph 5 says that malnutrition "can tip either way". The diagram shows what lies on each side.

Comprehension

What is the main idea of paragraph 1?
Which two nutrients does the writer call "fuel", and what do they do?
Name three good sources of protein from the article that do not come from animals.
Why is a lack of iron a problem for a student?
How many grams of fruit and vegetables should a fifteen-year-old aim to eat each day?
Explain how a person can be "overweight, yet short of iron and vitamins".
Why does the writer end with "a meal of beans, a sweet potato, a handful of green leaves and a banana"?
The writer uses three metaphors: fuel, bricks and shields. Choose one and explain why it fits.

Show answersHide answers

The body grows fast in adolescence and is built from food, so it needs a balanced diet: the right variety in the right amounts.
Carbohydrates and fats; they give the body energy.
Any three: beans, peas, groundnuts, soya.
Iron carries oxygen in the blood; too little causes anaemia, which makes a student tired and unable to concentrate.
At least 400 grams (everyone older than ten).
They may eat too much energy from sugar and fat, which causes overweight, but too few vegetables, fruits and pulses, so they lack iron and vitamins.
To show that a balanced meal can be local, cheap and simple, so expense is no excuse.
Sample: "Bricks" fits proteins because, like bricks in a wall, they are the material from which the body's muscles and organs are built and repaired.

Vocabulary: food groups and nutrition

Group	Main nutrients	Job in the body	Examples eaten in Rwanda
Energy foods	carbohydrates, some fats	fuel: energy for movement and thinking	sweet potatoes, cassava, maize, sorghum, rice, cooking bananas, avocado
Body-building foods	proteins	bricks: growth and repair	beans, peas, groundnuts, soya, milk, eggs, small dried fish, meat
Protective foods	vitamins, minerals, fibre	shields: fight infection, keep eyes, skin and blood healthy	amaranth, cassava leaves, carrots, pumpkin, mangoes, oranges, passion fruit

Useful phrase	Example
rich in / a good source of	Beans are rich in protein and a good source of iron.
high in / low in	Soft drinks are high in sugar and low in nutrients.
a lack of / a shortage of	A lack of iron can cause anaemia.
cut down on	Try to cut down on fried snacks.
a portion (serving) of	Eat a portion of green vegetables with every meal.

Worked example

One root, five words: the nutrition family

Complete: (a) Amaranth is a very ___ vegetable. (b) Ask a ___ about your diet. (c) Iron is a ___ that the blood needs.

List the family: nutrient (a substance, countable noun), nutrition (the process or science, uncountable), nutritious (adjective: full of nutrients), nutritional (adjective: connected with nutrition, as in nutritional value), nutritionist (a person).
Look at the gap: (a) after very and before a noun, so an adjective that describes food: nutritious. (b) after a, a person you ask: nutritionist. (c) after a, a thing the blood needs: nutrient.
Add the negative: malnutrition (n), malnourished (adj): A malnourished child needs medical help.

Worked example

Reading a food label

A packet of biscuits says, per 100 g: sugars 30 g; fat 20 g; salt 0.8 g. (Illustrative figures.) A student eats half the packet, 50 g. How much sugar is that, and how does it compare with the WHO limit?

Scale the label: 50 g is half of 100 g, so sugar = 30 ÷ 2 = 15 g.
Compare: the WHO's guide for an adult of healthy weight is under 50 g of free sugars a day; 15 ÷ 50 = 0.3, so 30% of the day's limit in one snack.
Say it in English: These biscuits are high in sugar: half a packet gives almost a third of the day's limit.

Tip

Fuel, bricks, shields. When you plan a meal, ask three questions: Where is my fuel? Where are my bricks? Where are my shields? If one is missing, the meal is not balanced.

Warning

Diet means all the food you usually eat. "To be on a diet" means to eat less, or in a special way, but a balanced diet is about variety, not hunger.
Dessert (sweet food after a meal) has double s; a desert is a dry, sandy place.
Lose weight (/luːz/), not loose weight: loose means not tight.
Fruit is usually uncountable: I eat a lot of fruit. Use fruits only for different kinds: tropical fruits such as mangoes and papayas.

A healthy diet, a healthier world, from the World Health Organization (about 2 minutes). List the pieces of advice in the video, then tick the ones that also appear in the article.

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Practice

Give the word from the glossary for: (a) a basic food that gives most of a people's energy; (b) a condition caused by too little iron; (c) dried seeds such as beans, peas and lentils.
Sort into fuel, bricks or shields: groundnuts, cassava, pumpkin, eggs, rice, oranges, sorghum, small dried fish, amaranth.
Complete with rich in, high in, a lack of, cut down on: (a) Fried snacks are ___ fat. (b) ___ vitamin A can harm the eyes. (c) Dark green leaves are ___ iron. (d) The doctor told my uncle to ___ salt.
Complete with a word from the nutrition family: (a) Sorghum porridge is a ___ breakfast. (b) The ___ value of soft drinks is very low. (c) The clinic treats ___ children.
A soft drink label says, per 100 ml: sugars 10 g. How much sugar is in a 500 ml bottle? Is that above or below the WHO's daily guide of 50 g for an adult?
True or false, according to the article? Correct the false ones. (a) Malnutrition only means eating too little. (b) The fats in avocado are a better choice than those in palm oil. (c) A balanced meal must include meat.
Plan a balanced lunch for a school canteen using only local foods. Write four sentences explaining where the fuel, the bricks and the shields are.

Show answersHide answers

(a) staple; (b) anaemia; (c) pulses.
Fuel: cassava, rice, sorghum. Bricks: groundnuts, eggs, small dried fish. Shields: pumpkin, oranges, amaranth.
(a) high in; (b) A lack of; (c) rich in; (d) cut down on.
(a) nutritious; (b) nutritional; (c) malnourished.
500 ml is 5 × 100 ml, so 5 × 10 = 50 g of sugar: the whole daily guide in one bottle.
(a) False: it means too little, too much or the wrong kinds of food. (b) True. (c) False: beans, peas, groundnuts and soya give protein too.
Open answer. Check that each of the three groups is present and correctly explained.

Sources and credits

Article "Fuel, Bricks and Shields", glossary, balance diagram, questions, tables, worked examples and practice: written by Ganzaa. The food label in the worked example is illustrative.
Health facts: Healthy diet, fact sheet, World Health Organization, updated 26 January 2026. Facts summarised, not copied.
Video: A healthy diet, a healthier world, World Health Organization, embedded from YouTube, not copied.

Written by Ganzaa.

1Before you read

2Reading: Fuel, Bricks and Shields

3Malnutrition: a balance that tips both ways

4Comprehension

5Vocabulary: food groups and nutrition

Before you read

Reading: Fuel, Bricks and Shields

Malnutrition: a balance that tips both ways

Comprehension

Vocabulary: food groups and nutrition