Peptides for weight loss, ranked by what the trials found

Peptides for weight loss: what works and what does not

The peptides for weight loss with strong human evidence are the GLP-1 drugs: tirzepatide (Zepbound), semaglutide (Wegovy) and liraglutide (Saxenda), and all three are authorized for weight management in Canada^1,2. In their main trials, average losses ran from 8.0% to 20.9% of body weight over 56 to 72 weeks, while the placebo groups lost 2.4% to 3.1%^3,4,5. The vials sold online as “research” peptides, like BPC-157, MOTS-c, AOD-9604 and CJC-1295 with ipamorelin, have no human trial showing weight loss and are not authorized for sale here^6,7.

That is the whole story in three sentences. The rankings table above sorts all 14 products by an evidence grade, and the rest of this page explains what sits behind each letter. Grades A and B mean randomized trials in people found real weight loss.

Grade C means the human data measured something other than body weight. Grade D means the case rests on mice, a failed program, or nothing at all. You can read the full rules in how we grade.

What are peptides for weight loss?

A peptide is a short chain of amino acids, the same building blocks that make up proteins⁸. Several hormones that steer blood sugar and appetite are peptides, including insulin and amylin^8,9. Insulin also opened the door for peptide medicines almost a century ago, and more than 80 peptide drugs have reached the market since¹⁰.

So the word is broad. It covers a Wegovy pen with a Drug Identification Number and an unlabelled vial from a website that calls itself a lab.

Health Canada names semaglutide and tirzepatide among the peptide drugs it has authorized⁸. The vial on the website has no such review behind it.

When people talk about weight loss peptides, they usually mean one of two very different groups. The first is prescription drugs with large trials and a Health Canada review.

The second is powders sold as research chemicals online and, in some cases, through wellness clinics, with no review at all^11,12. This page treats them separately because the evidence does.

Two items in our table are not peptides at all. Orforglipron is a small-molecule pill that acts on the GLP-1 receptor¹³, and 5-amino-1MQ is a small molecule that blocks an enzyme¹⁴. We list them because people shop for them under the peptide label.

How weight-loss peptides work, in plain words

Every peptide with solid weight-loss data copies a hormone from your gut or pancreas. Each one sends some version of the same message: you have eaten enough.

Hormone	Where it comes from and what it does	Drugs that copy it
GLP-1	Released by the gut after you eat. Raises insulin, lowers glucagon, slows how fast the stomach empties and cuts food intake15	Semaglutide, liraglutide, and part of tirzepatide, retatrutide, survodutide and CagriSema
GIP	Short for glucose-dependent insulinotropic polypeptide, a hormone that helps release insulin. Tirzepatide acts on both its receptor and GLP-1’s5	Tirzepatide, retatrutide
Glucagon	A pancreas hormone that works against insulin on blood sugar15. Newer drugs add it to the GLP-1 signal16,17	Retatrutide (with GIP and GLP-1), survodutide (with GLP-1)
Amylin	A 37-amino-acid hormone from the same pancreas cells that make insulin. It acts mainly in the brain9	Cagrilintide, the partner of semaglutide in CagriSema18

A fair warning about this table. Trials measure weight, not which hormone did the work. Adding a second or third target is a plausible reason the newer drugs do more, but nobody has proved it.

Which peptides for weight loss have real evidence

Eight products on our list have phase 3 trials with weight as the main result. Five of them are approved for weight somewhere, which earns an A. The other three have the trials but no approval, which earns a B.

Grade A: approved and proven. Tirzepatide, injectable semaglutide and liraglutide are sold in Canada for weight¹. The 25 mg semaglutide pill has a US weight approval¹⁹, with no Canadian one yet^1,2.

Orforglipron also earns an A on its US approval, with the not-a-peptide flag²⁰. If you are choosing between these, our guide to which GLP-1 to choose ranks them one by one, and the Mounjaro vs Ozempic head-to-head covers the trials that pitted two of them against each other.

Grade B: strong trials, no approval yet. Retatrutide, CagriSema and survodutide all have phase 3 papers in the New England Journal of Medicine^21,18,17. None is authorized in Canada¹, and we found no approval for any of them elsewhere as of November 2026.

CagriSema is under review by Health Canada, while retatrutide and survodutide are not²². A B is a promise, not a product.

The peptides with weak or no weight-loss evidence

These are the names that fill social feeds and medspa menus. Here is the honest summary: one has human data on belly fat in a narrow group, and the rest have nothing in people that shows weight loss.

Tesamorelin (grade C) copies the signal that tells the body to release growth hormone. In its main phase 3 trial, 412 people with HIV and abdominal fat gain took it daily for 26 weeks. Fat inside the belly, measured by CT scan, fell 15.2%, while it rose 5.0% on placebo²³.

Body weight was not the main outcome. Canada once approved it as Egrifta², but both Canadian DINs are now cancelled, so no tesamorelin is sold here¹.

Peptide (grade D)	What the best evidence shows
AOD-9604	A modified piece of human growth hormone, once developed as an oral obesity pill24. The program was ended in 2007 after phase IIb results25, and we found no peer-reviewed paper showing it worked.
MOTS-c	Stopped diet-induced obesity in mice26. The FDA says it has not identified any human exposure data6.
BPC-157	No human weight data. The published human work is tiny, such as a two-person safety pilot of intravenous use27.
CJC-1295 with ipamorelin	CJC-1295 raised growth hormone and IGF-I in healthy adults, with no weight result reported28. Ipamorelin’s lone phase 2 trial, in bowel surgery, did not beat placebo29. No trial has tested the pair.
5-amino-1MQ	Cut body weight and fat in obese mice without changing how much they ate14. No human data. Not a peptide.

Our take: a mouse result is where drug research starts, not where it ends. AOD-9604 shows how that can go, since it reached human trials and its obesity program was still dropped²⁵. Until one of these passes a real trial in people, we grade it D and publish no doses for it.

How much weight you can lose with peptides, and how long it takes

On the drugs sold in Canada, the average person in the trials lost somewhere between a twelfth and a fifth of their body weight, and it took more than a year to get there. This table shows each trial’s main result. Most count everyone who started, including people who stopped the drug; SCALE is older and used a different method³.

Trial	Drug and top dose	Length	Weight lost	Placebo
SCALE3	Liraglutide 3.0 mg daily	56 weeks	8.0%	2.6%
STEP 14	Semaglutide 2.4 mg weekly	68 weeks	14.9%	2.4%
OASIS 430	Oral semaglutide 25 mg daily	64 weeks	13.6%	2.2%
SURMOUNT-15	Tirzepatide 15 mg weekly	72 weeks	20.9%	3.1%
REDEFINE 118	Cagrilintide plus semaglutide, 2.4 mg each, weekly	68 weeks	20.4%	3.0%
SYNCHRONIZE-117	Survodutide 6.0 mg weekly	76 weeks	13.0%	5.4%
TRIUMPH-121	Retatrutide 12 mg weekly	80 weeks	25.0%	3.9%

Lower doses did less. In SURMOUNT-1, the 5 mg dose of tirzepatide gave 15.0%⁵, and in TRIUMPH-1 the 4 mg dose of retatrutide gave 17.6%²¹. Survodutide’s placebo group lost an unusually large 5.4%, so its gap over placebo is smaller than the headline suggests¹⁷.

Averages also hide a wide spread. In SURMOUNT-1, more than half of the people on the top tirzepatide dose lost a fifth or more of their weight, compared with 3% of the placebo group⁵.

People with type 2 diabetes tend to land lower, as the tirzepatide and semaglutide diabetes trials showed^31,32. REDEFINE 2 tested CagriSema in that group and found 13.7% against 3.4% on placebo³³, well short of the 20.4% in people without diabetes¹⁸.

Why so slow? Because the dose climbs first. On Wegovy, the Canadian label takes 16 weeks to reach the full 2.4 mg³².

SURMOUNT-1 spent its first 20 weeks raising the tirzepatide dose⁵. The fastest early number we have is from retatrutide’s phase 2 trial: 17.5% lost by week 24 on the 12 mg dose¹⁶. Saxenda builds in a checkpoint: its label says to stop if you have not lost 5% of your weight after 12 weeks on the full 3.0 mg daily dose³.

One caution on the weeks. A trial’s length is when the researchers measured, not proof that weight had stopped falling. And weight tends to return when the drug stops, which is covered in our guide to comparing the GLP-1s.

Are there oral peptides for weight loss?

Yes, one, but not for weight in Canada yet. Oral semaglutide at 25 mg a day cut weight by 13.6%, against 2.2% on placebo, over 64 weeks in OASIS 4³⁰.

The FDA approved it as the Wegovy pill on December 22, 2025¹⁹. Canada has no DIN or Notice of Compliance for that pill^1,2, though Novo Nordisk told Global News it has applied³⁴.

The semaglutide tablet you can buy here, Rybelsus, is approved only for type 2 diabetes³⁵. Orforglipron is a once-a-day weight-loss pill approved in the US, but it is a small molecule rather than a peptide, and it is still under Health Canada review^20,22.

Be wary of “oral BPC-157” capsules. Health Canada named oral BPC-157 capsules among unauthorized products in its November 2026 warning³⁶.

Side effects of peptides for weight loss

The GLP-1 drugs share one main problem: the gut. Nausea and diarrhea top the list, and in STEP 1 they were mostly short-lived⁴. Constipation and vomiting show up too³¹.

In OASIS 4, 74.0% of people on the pill reported a stomach-related side effect, against 42.2% on placebo³⁰. In REDEFINE 1, the figures were 79.6% on CagriSema and 39.9% on placebo¹⁸.

Few people quit over them. In SURMOUNT-1, side effects made 4.3% to 7.1% of people on tirzepatide stop treatment, against 2.6% on placebo⁵.

Retatrutide raised heart rate in its phase 2 trial, with the peak at 24 weeks¹⁶. All three Canadian weight brands also warn about thyroid C-cell tumours, a finding from rodent studies^31,32,3, which is worth raising with whoever prescribes for you.

Research peptides are a different kind of risk, because nobody has measured it. When Sports Medicine reviewed unapproved peptides in 2026, the authors called good human safety data scarce and flagged the potential for serious harm³⁷.

Twice in November 2026, Health Canada reported bacteria in unauthorized peptides sold in Canada^38,36. Our safety and legal guide goes through those findings.

Peptides for weight loss in Canada: what is legal and sold

Three peptide drugs are authorized and on sale here for weight management: Wegovy, Zepbound and Saxenda^1,2. Ozempic and Mounjaro contain the same drugs as Wegovy and Zepbound but carry diabetes-only labels in Canada, so a prescription for weight loss is off-label^2,39,32. Sevmia, a generic semaglutide with a weight indication, was approved in June 2026 but is not on shelves¹.

Next in line are orforglipron and CagriSema, both under Health Canada review²². Retatrutide is not under review, and Health Canada has seized vials sold under its name^22,11.

For the legal route, from who qualifies to what the pens cost and how online clinics work, see our guide to getting weight loss injections in Canada.

How to choose the best peptide for weight loss

Start with whether a medicine fits you at all. Canada’s obesity guideline calls obesity a chronic, relapsing disease.

It supports weight-loss medicine for adults whose BMI is at least 30, or at least 27 with a weight-related health problem, used together with nutrition, activity and psychological support⁴⁰. That guideline is from 2020, before Wegovy and Zepbound were authorized here, but the eligibility line matches their labels^31,32.

Then work through four questions:

1. Do you want the most weight loss? Tirzepatide has the biggest result among drugs on Canadian shelves⁵.
2. Can you handle a needle? If not, know that no pill is authorized for weight here yet, though orforglipron is under review²².
3. Weekly or daily? Wegovy and Zepbound are weekly pens. Saxenda is a daily shot³.
4. What can you afford? Prices for each sit in the rankings table above, and the injections guide covers insurance.

If you want a shortcut, take the one-minute quiz. Six questions sort you toward the options with trial evidence that fit your budget and how you feel about injections. Whatever you pick, it has to come from a pharmacy with a prescription⁴¹.

How we graded these peptides

We are an independent Canadian site, and no drug company pays for these grades. We pulled each Health Canada status from the government’s drug and approval databases on November 12, 2026^1,2. Trial numbers come from the journal papers, not company press releases, and we use the estimate that counts everyone who started the trial.

A pharmacist review of this page is pending. This page is general information, not medical advice.