Grade by Grade
C. Healthy Living · Healthy Living: Choices, Connections and Well-Being

Diets Under the Microscope: Dietary Choices, Diet Trends and Reliable Information

C2.1 C2.2 1.5About 70 minutes
Learning goals
  • I can describe common dietary choices (vegetarian, vegan, halal, kosher, gluten-free) and what each person needs to plan for.
  • I can evaluate popular diet trends for their possible nutritional drawbacks.
  • I can tell reliable nutrition information from unreliable information.
  • I can explain how to make informed food choices that meet my needs for healthy, active living.

Words to know

dietary choice
A long-term pattern of eating chosen for health, ethical, environmental, cultural or religious reasons, or because of a medical need.
diet trend
A popular way of eating that spreads quickly, often through social media, sometimes with little scientific evidence.
registered dietitian (RD)
A regulated health professional trained to give nutrition advice. In Ontario the title is protected by law.
celiac disease
A condition in which eating gluten (a protein in wheat, barley and rye) damages the small intestine.
fortified
Having nutrients added, such as vitamin D in milk and some plant-based beverages.
anecdote
A single personal story. Interesting, but not proof that something works for most people.

"I lost 5 kg in a week!"

Your feed is full of diets: keto, "clean eating", juice cleanses, fasting apps, "detox" teas. Some come from real science. Many come from people selling something. How do you tell the difference, and what do growing teens actually need?

The Grade 10 curriculum asks you to look at the effects of different dietary choices, to think critically about diet trends, and to use reliable information to make informed food choices (C2).

Dietary choices people make for good reasons

  • Vegetarian: no meat, poultry or fish. Many eat eggs and dairy. Plan protein (beans, lentils, tofu, eggs, dairy, nuts) and iron (legumes, fortified cereals; eat with vitamin C foods to help absorb it).
  • Vegan: no animal foods at all. Needs a reliable source of vitamin B12 (fortified foods or a supplement), plus planning for calcium, vitamin D, iron, zinc and omega-3 fats.
  • Halal (Muslim) and kosher (Jewish) diets follow religious rules about which foods are allowed and how they are prepared. Both can easily meet every nutrient need.
  • Gluten-free: essential for people with celiac disease. For people without it, gluten-free is not automatically healthier; some gluten-free packaged foods are lower in fibre and higher in sugar.
  • Allergy diets: avoiding peanuts, tree nuts, milk, eggs or other allergens, with careful label reading.
  • Traditional and cultural diets: for example, many First Nations, Métis and Inuit families eat traditional foods such as fish, game, wild rice and berries, which are nutrient-rich and culturally important.

Any of these can be healthy when it is planned to meet nutrient needs.

Same balance, different protein foodsvegetablesand fruitswholegrainschicken orfish, eggsOmnivore platevegetablesand fruitswholegrainsbeans, lentils,tofu, eggsVegetarian plateVegans skip eggs and dairy too, and need a vitamin B12 source (fortified foods or a supplement).
Canada's Food Guide plate works for many dietary choices: half vegetables and fruits, a quarter whole grains and a quarter protein foods. Only the protein choices change.

Diet trends: what to know

  • Very low-carbohydrate diets (like keto): cut out most grains, fruit and starchy vegetables, which are major sources of fibre, vitamins and the carbohydrate active teens use for energy. Side effects can include tiredness and constipation.
  • Intermittent fasting: long stretches without food. For growing, active teens, long fasts can mean missing energy and nutrients and can lead to the skip-then-overeat cycle. Health professionals generally don't recommend it for teens without medical guidance.
  • Juice cleanses and "detox" products: your liver and kidneys already remove waste. Juice-only plans are low in protein and fibre, and some detox teas contain laxatives.
  • "Clean eating" and cutting out whole food groups: can lead to missing nutrients and to anxiety about food. Strict food rules are a warning sign for disordered eating.
  • Supplements and protein powders: most teens can meet protein needs from food. Supplements are not tested the way medicines are, and some contain ingredients not on the label.
  • Plant-forward eating: eating more plant foods (without necessarily cutting out animal foods) is supported by Canada's Food Guide. Not every trend is bad!
Five questions to check any diet or nutrition claim1. Who?Who says so?A registereddietitian orhealthagency, orsomeonesellingsomething?2. Evidence?Studies inmany people,or one storyand beforeand afterphotos?3. Cuts?Does it dropwhole foodgroups theFood Guideincludes?4. Promise?Fast, easy,"miracle"results are ared flag.5. Fits me?Does it fitmy age,growth,activity,health,culture andbudget?Two or more warning answers? Ask a registered dietitian or doctor before trying it.
Run any diet or nutrition claim through these five questions before you try it or share it.

Reliable sources

  • Canada's Food Guide (Health Canada)
  • Registered dietitians: Ontario residents can call Health811 (dial 8-1-1) to speak with a registered dietitian for free
  • Your doctor, nurse practitioner or pharmacist
  • Unlock Food (from Dietitians of Canada)

Less reliable: influencers, celebrity diets, ads, anyone selling the product they're recommending.

Worked example

Let's evaluate a trend

A fitness influencer with 2 million followers posts: "Cut ALL carbs for 30 days. I dropped 6 kg and my skin is glowing! Use my code for 20% off my keto shakes." Evaluate it with the five questions.

  1. Who says so? An influencer, not a dietitian, and they earn money from the shakes. Warning.
  2. Evidence? One person's story and photos (an anecdote). Warning.
  3. What does it cut? All carbohydrates: grains, fruit, starchy vegetables and milk. That's most of the Food Guide plate. Warning.
  4. Promise? Fast weight loss and "glowing skin" in 30 days. Warning.
  5. Fit for me? A growing, active 15-year-old needs carbohydrate for energy and fibre for digestion. Doesn't fit.

Five warnings out of five. This is marketing, not reliable nutrition advice. A teen should not follow it without talking to a dietitian or doctor.

Worked example

Let's plan a balanced vegetarian day

Ravi, 15, has decided to become vegetarian (he will eat eggs and dairy). His mom asks how he'll get enough protein and iron. Plan one day.

  1. Breakfast: oatmeal made with milk, topped with berries and pumpkin seeds (protein, iron, calcium).
  2. Lunch: whole grain wrap with hummus, a hard-boiled egg and vegetables; an orange (vitamin C helps absorb iron).
  3. Snack: yogurt and an apple.
  4. Dinner: lentil and vegetable curry with brown rice; a glass of milk or fortified soy beverage.
  5. Check: protein at every meal (milk, egg, hummus, lentils, yogurt), iron from lentils, seeds and oats paired with vitamin C foods, and half the plate vegetables and fruit.

With a little planning, Ravi's vegetarian day meets his needs. If he later chooses to be vegan, he'll also need a B12 source.

Just for fun

A detox tea promises to "cleanse your system." Your liver and kidneys have been running a 24/7 cleansing service since before you were born, and they've never once asked for a discount code.

Hands-on activity

Food Guide versus the feed

You need: a device with Canada's Food Guide website, and two diet posts or ads you've seen (screenshots or notes).

  1. For each post, answer the five questions in a table.
  2. Count the warnings.
  3. Look up what Canada's Food Guide says about the same topic (for example, "Make water your drink of choice", "Be aware of food marketing", "Use food labels").
  4. Write a 3-sentence "reply" you could post that is kind, factual and cites a reliable source.

What to look for: each post judged on evidence and source (not on whether the person seems nice), at least one reliable source named, and a reply that doesn't shame anyone's body or food.

Your turn

1

What nutrient must vegans get from fortified foods or a supplement?

2

Who must eat gluten-free, and why?

3

Is gluten-free food automatically healthier for someone without celiac disease? Explain.

4

Name the five questions for checking a diet claim.

5

Give one possible drawback of a very low-carbohydrate diet for an active teen.

6

Why don't you need a detox product?

7

Name two reliable sources of nutrition information.

More practice: warm-up

1

What does a vegetarian not eat?

2

What proportion of the Food Guide plate is vegetables and fruits?

3

Is a single before-and-after story strong evidence?

4

What number can Ontario residents call to talk to a registered dietitian for free?

5

Which food helps your body absorb iron from plant foods?

More practice: on your own

1

Explain why a halal or kosher diet can be fully healthy.

2

A teammate drinks two protein shakes a day "to build muscle." What would you tell them?

3

Why is "intermittent fasting" a poor fit for most growing, active teens?

4

Rate this claim with the five questions: "Canada's Food Guide suggests making water your drink of choice."

5

Explain how a strict "clean eating" rule could harm someone's well-being, not just their nutrition.

Challenge

1

Compare a planned vegetarian diet with a 7-day juice cleanse. Which is a sustainable dietary choice, and why?

2

Create a social media post (3 to 4 sentences) that helps teens spot nutrition misinformation without shaming anyone.

3

Why might two healthy teens make very different dietary choices, and both be right?

Check your understanding

Quiz

1.

Which nutrient is the biggest concern for someone who eats a vegan diet without planning?

2.

Gluten-free eating is medically necessary for...

3.

Which is the strongest sign that a diet claim is unreliable?

4.

What already removes waste from your body, making "detox" products unnecessary?

5.

Which is the most reliable source for a teen's nutrition question?

6.

A very low-carbohydrate diet can leave an active teen low in...

For parents and teachers

Big idea: students evaluate the effects of different dietary choices and diet trends and use reliable sources to make informed food choices (overall expectation C2; critical thinking, Living Skill 1.5).

How to help at home: if your teen wants to try a new way of eating (for example, becoming vegetarian), treat it as a planning project together rather than a battle; Health811 (dial 8-1-1) connects Ontario residents with a registered dietitian at no cost. Be cautious about diets that restrict whole food groups, involve long fasts or promise fast weight loss; these are not recommended for growing teens.

Common difficulties: confusing popularity with evidence, and believing "gluten-free" or "natural" means healthier. Frequent dieting, rigid food rules or secrecy around food can be early warning signs of disordered eating; talk to your family doctor if you're concerned.

Facts used: Canada's Food Guide (Health Canada, 2019); vitamin B12 guidance for vegans; celiac disease and gluten. Ontario's Health811 service includes access to registered dietitians.