Western Zone Obesity Network · Patient Guide
A plain-language guide to the weight management medications available in Canada: how they work, what to expect, and how to choose with your care team.
It’s Not About Willpower
If you have struggled with your weight, you know how hard it can be. You may have tried many diets and lost weight, only to gain it back. This is not your fault. Scientists now understand that obesity is a chronic disease: your brain has powerful systems that control hunger, cravings, and how your body stores fat, and these systems are not under your conscious control. That is why willpower alone usually is not enough.
Weight management medications work by targeting the brain systems that control appetite. They do not give you willpower. Instead, they work on the automatic, non-conscious parts of your brain that drive hunger and cravings. Think of it this way: these medications help quiet down the constant “noise” of hunger signals, making it easier to make healthy choices and stick with them.
“Pharmacotherapy is an effective and safe approach to treating obesity. As with other chronic diseases such as type 2 diabetes or high blood pressure, medication is an important part of obesity management.”
Different medications lead to different amounts of weight loss. On average, the newest medications (tirzepatide and semaglutide 2.4 mg) can help people lose around 15% of their body weight, while older medications typically help with 5–10%. Some people lose more, some less; everyone responds differently. For someone who weighs 220 pounds (100 kg), a 15% loss is about 33 pounds, and a 10% loss is about 22 pounds.
Even a 5–10% weight loss can greatly improve your health, helping with blood sugar, blood pressure, cholesterol, joint pain, sleep apnea, and energy levels.
At a Glance
Health Canada has approved six medications for long-term weight management. Here is how the five most commonly discussed options compare:
| Medication | How taken | How often | How it works | Avg. weight loss* |
|---|---|---|---|---|
| Tirzepatide Zepbound / Mounjaro | Injection under skin | Once weekly | Copies two gut hormones (GLP-1 & GIP) | 15–22% |
| Semaglutide Wegovy | Injection under skin | Once weekly | Copies the GLP-1 gut hormone | 15–17% |
| Liraglutide Saxenda | Injection under skin | Once daily | Copies the GLP-1 gut hormone | 5–7% |
| Naltrexone / Bupropion Contrave | Pills by mouth | Twice daily | Acts on appetite & reward centres | 4–6% |
| Orlistat Xenical | Pills by mouth | Three times daily | Blocks some fat absorption | 2–3% |
*Average weight loss beyond what would be expected with lifestyle changes alone. Individual results vary.
Eligibility
According to Obesity Canada guidelines, weight management medications may be right for you if:
Your doctor will also consider your waist measurement and overall health when deciding if medication is right for you. The detailed profiles below focus on the three options most often prescribed through our network: tirzepatide, semaglutide, and Contrave.
GLP-1 Based Medications
The most effective weight loss medications work by copying a natural hormone in your body called GLP-1 (glucagon-like peptide-1). Your gut makes this hormone after you eat, and it tells your brain that you are full.
Tirzepatide is the newest and most effective weight loss medication available. It works by copying two natural gut hormones instead of just one, and this double action leads to greater weight loss than older medications.
In clinical studies of people without diabetes, average weight loss was 15–22% of starting body weight.
Tirzepatide is started low and increased slowly every 4 weeks to reduce side effects:
| Week | Dose |
|---|---|
| Weeks 1–4 | 2.5 mg |
| Weeks 5–8 | 5 mg |
| Weeks 9–12 | 7.5 mg |
| Weeks 13–16 | 10 mg |
| Weeks 17–20 | 12.5 mg |
| Week 21+ | 15 mg (maximum) |
Not everyone needs to reach the highest dose. Work with your doctor to find the dose that works best for you. If side effects bother you, it is okay to stay at a lower dose longer, or not increase at all.
Semaglutide was the first of the highly effective GLP-1 medications approved for weight loss. It has been well-studied and shown to provide significant, lasting weight loss.
In clinical studies, average weight loss was about 15–17% of starting body weight.
Semaglutide is also started low and increased every 4 weeks:
| Week | Dose |
|---|---|
| Weeks 1–4 | 0.25 mg |
| Weeks 5–8 | 0.5 mg |
| Weeks 9–12 | 1.0 mg |
| Weeks 13–16 | 1.7 mg |
| Week 17+ | 2.4 mg (target dose) |
Semaglutide has been shown to reduce the risk of heart attack and stroke in people with heart disease, help people with prediabetes return to normal blood sugar, improve symptoms in people with heart failure, and reduce knee pain in people with osteoarthritis.
Other Options
Contrave combines two medications used for other conditions: bupropion (an antidepressant) and naltrexone (used for alcohol and opioid dependence). Together, they work on the brain’s reward system to reduce cravings and appetite. It may be a good choice if you prefer pills over injections, struggle with food cravings or emotional eating, or also have depression.
Common side effects: nausea, constipation, headache, dizziness, trouble sleeping, dry mouth.
People with uncontrolled high blood pressure, a history of seizures, those taking opioid pain medications, those with eating disorders (anorexia or bulimia), or anyone suddenly stopping alcohol or sedatives.
Liraglutide (Saxenda) is a daily GLP-1 injection with more modest weight loss (5–7%); it is used less often now that weekly GLP-1 options are available. Orlistat (Xenical) is a pill taken three times daily that blocks some fat absorption from food (2–3% weight loss) and is rarely used in modern obesity care. Your care team can tell you whether either fits your situation.
What to Expect
The most common side effects of GLP-1 medications are digestive: nausea, diarrhea or constipation, and feeling full quickly. They are usually worst when you first start or increase the dose.
For most people, side effects get better over 2–4 weeks as your body adjusts. Starting low and increasing slowly is the best way to reduce them.
People with a personal or family history of medullary thyroid cancer, or Multiple Endocrine Neoplasia syndrome type 2 (MEN 2). People with a history of pancreatitis should use them only with caution and after medical evaluation of the risks and benefits.
Practical Information
One of the biggest barriers to weight management medications is cost. Without insurance, these medications cost approximately $300–$800 per month. Many private plans now cover them, especially for diabetes, and coverage for weight management is improving but varies by plan. You may need a “prior authorization” form from your doctor.
Ask your pharmacist about manufacturer savings programs, and check the official savings cards (often a 25–40% discount):
Store unopened injection pens in the refrigerator (2–8°C); do not freeze. An in-use pen can be kept at room temperature (below 30°C) for up to 4 weeks. For weekly injections, if it has been less than 4–5 days since a missed dose, take it as soon as you remember; if longer, skip it and take your next dose on the regular day. Never take two doses to make up for a missed one.
The Long View
Weight management medications are meant to be taken long-term, just like medications for blood pressure or diabetes. Stopping the medication usually leads to weight regain.
Obesity is a chronic disease. The brain systems that drive hunger and weight gain do not go away. When you stop the medication, hunger signals return to their previous levels, cravings often come back, and weight regain is common and expected. This is not a failure. It is biology. The medication helps manage the disease, but it does not cure it, just as blood pressure medication controls but does not cure high blood pressure.
If you reach a weight that feels right for you, continue the medication to maintain your results, though your doctor may be able to lower the dose. Medication works best combined with healthy eating, adequate protein, regular activity, good sleep, and stress management.
Appendix
Using a higher-dose pen with the “click-counting” method can lower costs if you are paying out of pocket. This is an off-label way of delivering the medication, so some physicians and pharmacists may not be comfortable with it. Always discuss it with your care team first.
Each 15 mg pen has 240 clicks; 60 clicks delivers the full 15 mg dose, which is not something you want to do in week 1. The pen locks out after 240 clicks, so count carefully. Always use a new pen tip, avoid touching the needle, and return the pen to the fridge immediately. Stay a minimum of 4 weeks on each dose, and do not increase if you are having side effects.
| Dose (mg) | Clicks | Doses in a full pen |
|---|---|---|
| 2.5 | 10 | 24 |
| 5 | 20 | 12 |
| 7.5 | 30 | 8 |
| 10 | 40 | 6 |
| 12.5 | 50 | 5 |
| 15 | 60 | 4 |
74 clicks delivers the full 2.4 mg dose; the typical 0.25 mg starting dose is around 7 clicks. The usual plan steps up every 4 weeks. The same safety rules apply: new pen tip each time, do not touch the needle, refrigerate after use, and at least 4 weeks per dose.
| Dose (mg) | Clicks | Doses in a full pen |
|---|---|---|
| 0.25 | 7 | 42 |
| 0.375 | 11 | 26 |
| 0.5 | 15 | 20 |
| 0.75 | 23 | 12 |
| 1 | 30 | 9 |
| 1.25 | 38 | 7 |
| 1.5 | 46 | 6 |
| 1.75 | 54 | 5 |
| 2 | 62 | 5 |
| 2.4 | 74 | 4 |
Before Your Appointment
Here are some questions you may want to discuss with your healthcare team. Tap any question to read more.
There is no single best medication for everyone. Your doctor will weigh how much weight loss you are aiming for, your other health conditions, whether you prefer pills or injections, your insurance coverage, and how you tolerate side effects. The newer GLP-1 medications are the most effective, but the right choice is the one that fits your situation and that you can stay on.
It depends on the medication. The newest options (tirzepatide, semaglutide) average 15–22% and 15–17% of body weight; older options average 2–10%. Some people lose more and some less. Even a 5–10% loss brings meaningful health benefits.
Most side effects are digestive (nausea, constipation or diarrhea, feeling full quickly) and improve over 2–4 weeks. Rare but important ones include gallstones and pancreatitis. Seek medical help for severe stomach pain that does not go away.
Obesity is a chronic disease, so these medications are meant for long-term use, like blood pressure or diabetes medication. Stopping usually leads to weight regain because the hunger signals return. This is biology, not failure.
Coverage varies by plan and is improving, especially for diabetes. You may need a prior authorization form. If cost is a barrier, ask about manufacturer savings cards. If you do need to stop, talk with your team about a maintenance plan to limit weight regain.
Often, yes. Medication works best alongside healthy eating, adequate protein, activity, good sleep, and stress management. A registered dietitian and other members of the care team can help you get the most from treatment.
This guide is for educational purposes only and does not replace advice from your healthcare provider. Always talk to your doctor or nurse practitioner before starting, stopping, or changing any medication. Based on Obesity Canada Clinical Practice Guidelines (2025 Update).
Keep Going
Medications are one of three pillars of care. Learn how obesity works, take the free course, or find out how to access care.
Get in Touch
Questions about medications, care, or resources? Reach out, we’d love to hear from you.