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I want to lose a few kilos before an event. Should I try a GLP-1?

An honest answer for anyone eyeing a weight-loss injection before a wedding, a holiday or a big day.

GLP Guidebook teamUpdated 12 Oct 20263 min read13 sourcesWritten from published sources
The short answer

Probably not. In Canada, GLP-1 medicines are approved for type 2 diabetes, and some brands for obesity or overweight with a related health problem, not for a few kilos. The Canadian obesity guideline treats them as long-term treatment for a chronic disease. They take months to reach full dose, often upset the stomach, and the weight usually returns when you stop. There are better ways to feel good on the day.

Read this page first. It covers why these medicines aren't meant for a few kilos, what happens after, the fakes and what works instead. At the end, three guides take you further, in order.
On this page
  1. Why it isn't meant for this
  2. Would it work in time?
  3. After the event
  4. The fakes problem
  5. What works instead
  6. What to read next
  7. Sources

Why isn't it meant for this?

These medicines treat a disease. They aren't meant for fine-tuning your weight.

Wanting to look and feel your best on a big day is completely normal. But the Canadian obesity guideline describes these medicines as long-term treatment for obesity, a chronic disease, used together with health behaviour changes.2

Here are the lines that matter in Canada:

  • The label. Wegovy and Zepbound are approved for weight management in adults with a BMI (body mass index, your weight compared with your height) of 30 or more, or 27 to under 30 with at least one weight-related health problem, such as high blood pressure.3
  • The healthy range. The Canadian guideline counts a BMI of 18.5 to 24.9 as healthy for most adults. Overweight starts at 25, or at 23 for adults of South, Southeast or East Asian background.4
  • Who pays. No provincial drug plan covers these medicines for weight management, so it would be private insurance or your own money.11
  • Ozempic and Mounjaro. In Canada they are approved for type 2 diabetes only, not for weight loss.3

So if you're in the healthy range, or just above it, these medicines aren't approved for you.

Would it even work in time?

Not really. The dose goes up slowly, over about 4 months.

Wegovy starts at 0.25 mg and steps up every 4 weeks. It reaches the full dose of 2.4 mg after 16 weeks.1

Feeling sick and diarrhea were the most common side effects in STEP 1, the main semaglutide weight trial. People there got either the medicine or a dummy injection with no medicine in it. More people stopped because of stomach effects on the medicine.5

Out of every 100 people, how many stopped because of stomach effects:

STEP 1Semaglutide 2.4 mg (Wegovy), weekly

1,961 adults with obesity or overweight and no diabetes, 68 weeks.5

Semaglutide4.5 in 100
Dummy injection0.8 in 100

Bars are drawn on a scale up to 10 in 100.

Not ideal in the weeks before a celebration. The Canadian guideline recommends using these medicines long term, not as a short course.2

What happens after the event?

The weight usually comes back once you stop.

A year after stopping semaglutide, people followed up from STEP 1 had regained about two-thirds of the weight they lost.6 Most of their gains in blood pressure, sugar and cholesterol faded too.6

What about the fakes?

Fake and illegal GLP-1s are sold in Canada. Buying without a proper consultation, from unlicensed sellers, raises the risk of getting one.

  • The WHO has found falsified Ozempic in Brazil, the UK and the US. Fakes may be missing the medicine, or contain a different one, such as insulin.12
  • Health Canada warns about fake or unauthorized Ozempic and Mounjaro sold in stores and online, some with misused logos and fake endorsements. It says to buy only from a licensed pharmacy and check the 8-digit DIN.7
  • In August 2025 it warned that injectable "peptides", including tirzepatide and retatrutide, sold online were illegal in Canada.8
Get help now. If you've injected a pen of unknown origin and feel shaky, confused or faint, call 911. You can also call a poison centre on 1-844-POISON-X (1-844-764-7669).13

So what works instead?

A plan built around food and movement, started as early as you can.

The WHO says medicines alone won't solve weight problems. Healthy eating and physical activity remain the base of treatment.9 Guide 3: Your options sets out what the evidence says about each option.

And if your weight is affecting your health, that's a different conversation. Guide 1: Weight and health helps you check where you stand.

Your optionsConsidering it for weightStopping

What to read next, in order

These three guides go deeper. Each one ends with a link to the next, so you can read them one after another.

  1. 1Should I consider a GLP-1? And when not toGuide 4 of 9DecideThe section on losing a few kilos: who these medicines are for, and who they're not for.
  2. 2Your options, and where medicines fitGuide 3 of 9DecideFood, activity and other options, with what the evidence says about each.
  3. 3Stopping and the long termGuide 9 of 9Live with itWhat happens to weight, and to your body, when people stop.
Was this page easy to understand?

Sources

  1. Novo Nordisk. Wegovy (semaglutide) US prescribing information, revised June 2026. Sections 1, 2.2, 5.2, 5.3, 5.5, 8.3, 17. (US label.) PDF
  2. Pedersen SD et al. Canadian Adult Obesity Clinical Practice Guideline: Pharmacotherapy for Obesity Management in Adults, 2025 update. Obesity Canada, Version 3, 11 August 2025 (obesity as a chronic disease; long-term use; pregnancy notes). obesitycanada.ca (PDF)
  3. Health Canada product monographs: Wegovy (revised 2 October 2026) and Zepbound (11 June 2026), indications; Ozempic (13 July 2026) and Mounjaro (23 June 2026), type 2 diabetes. Wegovy · Zepbound · Ozempic
  4. Rueda-Clausen CF et al. Canadian Adult Obesity Clinical Practice Guidelines: Assessment of People Living with Obesity. Obesity Canada, Version 1, 4 August 2020 (Table 1). obesitycanada.ca (PDF)
  5. Wilding JPH et al. Once-weekly semaglutide in adults with overweight or obesity (STEP 1). NEJM, 2021;384:989–1002. 1,961 adults without diabetes, 68 weeks. DOI
  6. Wilding JPH et al. Weight regain and cardiometabolic effects after withdrawal of semaglutide: the STEP 1 trial extension. Diabetes, Obesity and Metabolism, 2022;24(8):1553–1564. 327 people followed for a year after stopping. DOI
  7. Health Canada. Thinking about buying GLP-1 drugs like Ozempic or Mounjaro? Beware of fake or unauthorized products (advisory RA-81518), updated 21 January 2026. recalls-rappels.canada.ca
  8. Health Canada. Unauthorized injectable peptide drugs seized and sold in Canada (advisory), 1 August 2025. recalls-rappels.canada.ca
  9. World Health Organization. WHO issues global guideline on the use of GLP-1 medicines in treating obesity. 1 December 2025. Link
  10. Novo Nordisk. Ozempic (semaglutide) injection, US prescribing information and Medication Guide, revised May 2026. Sections 4, 5.3, 5.5, 5.6, 7.2, 8.5. (US label.) PDF
  11. BC PharmaCare. Drug coverage decision: semaglutide (Wegovy), 18 December 2025 ("Non-benefit"). Status of public plans checked 12 October 2026. gov.bc.ca (PDF)
  12. World Health Organization. WHO issues warning on falsified medicines used for diabetes treatment and weight loss. 20 June 2024. Link
  13. Health Canada. Canada launches new toll-free 1-844-POISON-X number for poison centres. 20 March 2023. canada.ca

Last checked 12 Oct 2026 · Next review due Jan 2027

How this page was made. Written by the GLP Guidebook team from the sources above: Canadian and US drug labels, published trials, the Canadian obesity guideline, WHO guidance and Health Canada pages. It's general information, not medical advice. Talk to your family doctor, nurse practitioner or pharmacist before starting, stopping or changing any medicine. In an emergency, call 911. How we write