C. Healthy Living · Healthy Living: Informed Choices for Body, Mind and Relationships

Fuel and Building Blocks: Nutrients, Energy and Activity

C2.1About 70 minutes

Learning goals

I can name the six kinds of nutrients and explain what each one does for my body.
I can explain where food energy comes from and how much each macronutrient gives.
I can explain how my food needs change with my activity level and growth.
I can choose foods from Canada's Food Guide groups that provide the nutrients I need.

Words to know

nutrient
A substance in food that your body needs to grow, repair itself, work properly and have energy.

macronutrients
Nutrients needed in large amounts that give energy: carbohydrates, proteins and fats.

micronutrients
Vitamins and minerals: needed in small amounts, but essential for health.

Calorie (food energy)
A unit of energy in food. One food Calorie is 1 kilocalorie, about 4.2 kilojoules (kJ). Canadian labels list Calories.

fibre
A carbohydrate in plant foods that your body cannot digest. It helps digestion and helps you feel full.

essential amino acids
Building blocks of protein that your body cannot make, so they must come from food.

energy balance
The match between energy taken in from food and drinks and energy used by your body.

Why does a hockey player eat so much?

A Grade 9 player in a two-hour practice, a long-distance runner and a student who mostly sits all need food, but not the same amount and not always in the same way. To understand why, you need to know what is inside food: nutrients.

The Grade 9 curriculum asks you to apply your knowledge of basic nutritional principles and healthy eating practices to develop a healthy eating plan (C2.1). This lesson builds the knowledge; the next lesson applies it to an eating plan.

Remember from Grade 8

In Grade 8 you evaluated your eating with Canada's Food Guide: a plate that is half vegetables and fruits, a quarter whole grain foods and a quarter protein foods, with water as the drink of choice. Now we look at why that plate works, nutrient by nutrient.

The six kinds of nutrients

Nutrition scientists group nutrients into six kinds. Three of them, the macronutrients, give you energy:

Carbohydrates: your body's main fuel, especially for your brain and for hard exercise. Found in whole grains, vegetables, fruits, legumes and milk. Includes sugars, starches and fibre.
Proteins: building blocks for muscles, organs, skin, hair, enzymes and the immune system. Made of amino acids; nine are essential and must come from food. Found in meat, fish, eggs, dairy, beans, lentils, tofu, nuts and seeds.
Fats: stored energy, help absorb vitamins A, D, E and K, and are part of every cell. Unsaturated fats (in nuts, seeds, avocado, fish, vegetable oils) are the healthier choice; saturated fats (in fatty meats, butter, cheese) are best in smaller amounts. Industrially made trans fats (partially hydrogenated oils) have been banned from foods in Canada since 2018.

The other three give no energy but are just as important:

Vitamins like vitamin C (immune system, healing) and vitamin D (bones; hard to get from sunlight in a Canadian winter, so milk is fortified with it).
Minerals like calcium (bones and teeth), iron (carries oxygen in blood) and potassium (muscles and nerves).
Water: about 60% of your body. It controls body temperature, carries nutrients and removes waste.

Gram for gram, fat has more than twice the energy of carbohydrate or protein. That doesn't make fat bad; it is just more energy-dense. Vitamins, minerals and water give no energy.

Nutrient	Main job	Good sources (Food Guide group)
Carbohydrate	Main energy source; fibre aids digestion	Oats, brown rice, whole wheat bread (whole grains); apples, carrots (vegetables and fruits); lentils (protein foods)
Protein	Growth and repair of muscles and tissues	Chicken, fish, eggs, tofu, beans, nuts, milk, yogurt (protein foods)
Fat (unsaturated)	Stored energy, absorbs vitamins A, D, E, K	Salmon, walnuts, sunflower seeds, avocado, canola oil
Calcium	Strong bones and teeth	Milk, yogurt, cheese, fortified soy beverage, canned salmon with bones, tofu made with calcium
Iron	Carries oxygen in the blood	Red meat, beans, lentils, spinach, iron-fortified cereal (eat with vitamin C foods to absorb more)
Vitamin D	Helps absorb calcium for bones	Milk and fortified soy beverage, fatty fish like salmon, eggs
Vitamin C	Immune system, healing, absorbs iron	Oranges, strawberries, red peppers, broccoli
Water	Temperature, transport, waste removal	Water, milk, and foods like fruits, vegetables and soup

Key nutrients for Grade 9 students. Teens need a lot of calcium and vitamin D because bones grow fastest in the teen years.

Energy in, energy out

Every nutrient label lists Calories. Your body uses energy in three ways:

At rest: breathing, heartbeat, brain activity, keeping warm. This is the biggest share for most people.
Digesting food: a small share.
Physical activity: the share you control most. A long practice burns much more than sitting.

Teens also need energy and nutrients for growth. When energy in and energy out roughly match over time, body weight stays fairly steady (while you grow). Bodies naturally come in many healthy shapes and sizes. In Grade 9 the goal is not counting Calories or dieting: it's eating enough of the right foods to fuel your activity and growth.

Energy in comes only from food and drinks. Energy out includes your body at rest, growing, digesting and moving. An active, growing teen has a bigger "energy out" side.

Matching food to activity

Before activity (1 to 3 hours ahead): a meal or snack with carbohydrates for fuel, like a whole grain bagel with peanut butter (or a seed butter, if your school is nut-free) and a banana.
During activity of about an hour: water is usually enough.
After activity: carbohydrate plus protein to refuel and repair, like yogurt and fruit, or chocolate milk and an apple.
More activity means a bigger appetite. Listen to hunger and fullness cues: eat when hungry, stop when comfortably full.

Worked example

Let's find the nutrients in a lunch

Jordan's lunch: a whole wheat wrap with chicken, lettuce and tomato; a glass of milk; an orange. Name the main nutrients and their jobs.

Whole wheat wrap: carbohydrates for energy, plus fibre.
Chicken: protein to build and repair muscle; also iron.
Lettuce and tomato: vitamins, minerals, fibre and water.
Milk: protein, calcium and vitamin D for bones; also water.
Orange: vitamin C (which also helps absorb iron), fibre and natural sugars for energy.

Jordan's lunch has all six kinds of nutrients: carbohydrates, protein, some fat (chicken, milk), vitamins, minerals and water. It also matches the Food Guide plate: vegetables and fruits, a whole grain, protein foods and a healthy drink.

Worked example

Let's compare two athletes' needs

Leah swims 90 minutes, 5 days a week. Her twin Noor does 30 minutes of walking most days. Who needs more food energy, and which nutrients matter most for Leah?

Both are growing teens, so both need nutrients for growth.
Leah's energy out is much larger because of long, hard training.
She needs more carbohydrates to fuel training and more protein after training to repair muscle.
She needs plenty of water, since you sweat even in a pool.
Noor's needs are lower but still important: the same healthy plate, in smaller amounts.

Leah needs more food energy. She should add carbohydrate-rich snacks before training and carbohydrate plus protein after, and drink water. Both twins follow the same Food Guide pattern; the amounts differ.

Just for fun

Riddle: Why did the banana go to the doctor?

It wasn't peeling well. (Bananas are a classic pre-practice carbohydrate, so it had better recover by game day.)

Hands-on activity

Nutrient detective in your kitchen

You need: 5 packaged foods from your kitchen with Nutrition Facts tables (e.g. cereal, crackers, yogurt, canned beans, peanut butter), paper and a pencil.

For each food, write the serving size and the grams of carbohydrate, protein and fat per serving.
Calculate the energy from each macronutrient: carbohydrate g × 4, protein g × 4, fat g × 9. Add them up.
Compare your total to the Calories on the label. It should be close (labels round their numbers).
Which food is the best source of protein? Of fibre? Of calcium (look at the % Daily Value)?

What to look for: correct multiplication, totals close to the label, and clear reasons for each "best source". Example: a yogurt with 6 g carbohydrate, 10 g protein and 3 g fat gives 24 + 40 + 27 = 91 Calories, close to a label showing 90.

Your turn

Name the three macronutrients.

Which nutrients give no energy?

How many Calories are in 10 g of fat?

What is the main job of protein?

Why is vitamin D often added to milk in Canada?

A snack has 20 g carbohydrate, 5 g protein and 2 g fat. How many Calories?

What should you eat after a hard practice, and why?

More practice: warm-up

What nutrient is about 60% of your body?

Which mineral carries oxygen in your blood?

Name one food high in fibre.

Which has more energy per gram: carbohydrate or fat?

What drink is usually enough during an hour of exercise?

More practice: on your own

Explain why someone who is vegetarian can still get enough protein. Give three sources.

Why do teens need lots of calcium and vitamin D?

A granola bar label says 6 g fat, 25 g carbohydrate, 3 g protein. Calculate its Calories and the percent that comes from fat.

Why might eating spinach with a red pepper help your body more than spinach alone?

Ali says, "Fat is bad, so I'll eat zero fat." Explain why this is not a good plan.

Challenge

A 90-minute hockey practice starts at 5:00 p.m. and you finish school at 3:15. Plan what and when to eat before and after, and explain the nutrients.

Two cereals have the same Calories per serving. Cereal A has 1 g fibre and 12 g sugars; Cereal B has 6 g fibre and 4 g sugars. Which is the better choice for a morning of classes, and why?

Explain why "energy in = energy out" is not the whole story of healthy eating for a teen.

Check your understanding

Quiz

Which group lists only macronutrients?

How many Calories does 1 gram of fat provide?

What is the main job of carbohydrates?

Which nutrient helps your body absorb calcium?

After a hard practice, which snack best helps you refuel and repair?

A snack has 10 g carbohydrate, 4 g protein and 5 g fat. How many Calories?

For parents and teachers

Big idea: This lesson builds the nutrition knowledge for C2.1: apply their knowledge of basic nutritional principles and healthy eating practices to develop a healthy eating plan (this lesson covers nutrients, food energy, activity level and Canada's Food Guide). The next lesson applies it to labels, cooking methods and a healthy eating plan.

Facts used: 4 Calories per gram of carbohydrate and protein, 9 per gram of fat; industrially produced trans fats (partially hydrogenated oils) banned in Canadian foods since 2018; Canada's Food Guide (2019).

How to help at home:

Read Nutrition Facts tables together while shopping.
Plan pre- and post-practice snacks with your teen.
Keep the focus on fuel and nutrients, not weight. If your teen talks about restricting food, skipping meals to lose weight or feeling guilty about eating, talk with your family doctor; these can be early warning signs of an eating disorder.

Common difficulties: forgetting the 9 for fat in Calorie calculations; thinking all fat or all carbohydrates are "bad"; thinking vitamins give energy.