Peptide Science Desk

Peptides vs GLP-1: what's the difference?

GLP-1 drugs are peptides

"GLP-3" (retatrutide) is still in testing and is not FDA approved.

By the Peptide Science Desk Editorial TeamFact-checked against FDA and official sources · Not yet reviewed by a licensed clinician. How we check facts

Short answer: Peptides vs GLP-1: GLP-1 drugs are one kind of peptide, so they are not the same thing. Ozempic is a peptide, but peptides are not the same as Ozempic. And GLP-1 is not the same as Zepbound: Zepbound (tirzepatide) is one GLP-1 and GIP drug. GLP-1 drugs are peptides. Semaglutide (Ozempic, Wegovy) and tirzepatide (Zepbound, Mounjaro) are FDA-approved peptide medicines. "Peptides" sold online, like BPC-157, are different, and BPC-157 is not a GLP-1 drug. "GLP-3" is a nickname for retatrutide, which is still being tested and is not approved. New to peptides? Start here: what are peptides?

GLP-1 guide: how it works, the full drugs list and side effects

Aerial view of the large brick NIH Clinical Center hospital buildings in Bethesda
The NIH Clinical Center in Bethesda, Maryland, a research hospital where many clinical trials take place.Photo: National Institutes of Health, public domain

Is semaglutide a peptide?

  • Yes. GLP-1 stands for "glucagon-like peptide-1." It is a natural peptide hormone in your body.
  • Semaglutide (Ozempic, Wegovy), tirzepatide (Zepbound, Mounjaro), and liraglutide (Saxenda, Victoza) are lab-made peptide medicines that work on the GLP-1 switch.
  • One exception: the pill orforglipron (Foundayo) works on the same switch, but it is not a peptide. A 2023 study calls it a "nonpeptide" drug.
  • So "peptides vs GLP-1" is a bit like "fruit vs apples." Most GLP-1 drugs are one kind of peptide.
Free 2-minute quizWhich GLP-1 or peptide option fits you?Compare Wegovy, Zepbound, Ozempic and more by your goal, cost and health flags. Nothing you pick is stored. Take the GLP-1 quiz

Peptides vs GLP-1: what is the difference?

  • When people online say "peptides," they often mean products like BPC-157, TB-500, or CJC-1295. Most of those are not FDA-approved medicines.
  • Approved GLP-1 drugs went through big trials in thousands of people. Their FDA labels list side effects.
  • In big trials, adults on semaglutide or tirzepatide lost about 15% to 21% of their weight on average.
  • AOD-9604, sold online for fat loss, has published results in rats, not people.

Is BPC-157 a GLP-1?

  • No. BPC-157 is not a GLP-1 drug. It is not approved for weight loss or anything else.
  • People talk about it for healing injuries and the gut. A 2026 review found only 3 small human studies and rated the proof "very low."
  • The FDA says it has no, or only limited, safety data on BPC-157 for the ways people use it.

What is GLP-3?

  • "GLP-3" is not an official drug name. It is an online nickname for retatrutide, a test drug made by Eli Lilly.
  • Retatrutide works on 3 hormone switches: GLP-1, GIP, and glucagon. Semaglutide works on 1 (GLP-1). Tirzepatide works on 2 (GLP-1 and GIP).
  • In a 48-week trial of 338 adults, people on the highest dose lost about 24% of their weight on average, vs about 2% on placebo. Stomach problems were the most common side effects, and heart rate went up for a while.
  • It is not FDA approved. The FDA says retatrutide cannot be used by compounding pharmacies, and it has warned companies that sold it as a "research" product to people.

GLP-3 vs GLP-1: which is stronger?

  • In separate trials, retatrutide’s average weight loss looked bigger.
  • But different trials had different people and different lengths, so you cannot fairly compare their numbers.
  • Bigger retatrutide trials are still running, and the FDA has not reviewed it. Only a head-to-head trial can show which works better.

Peptides vs GLP-1 side effects

  • Semaglutide: nausea and diarrhea were the most common side effects in its big weight trial. They were usually mild to medium and faded with time.
  • Tirzepatide: stomach side effects were most common, mostly mild to medium, mainly while the dose was going up.
  • Most unapproved peptides were tested in so few people that their side effects are mostly unknown. Unknown is not the same as safe.

The numbers in charts

Weight loss in big obesity drug trials

% of starting body weight lost, drug vs placebo (fake shot)

Different trials, different people: not a head-to-head comparison.

Show the numbers as a table
Weight loss in big obesity drug trials: % of starting body weight lost, drug vs placebo (fake shot)
TrialDrugPlacebo
Tirzepatide 15 mg (Zepbound)
SURMOUNT-1 · 2,539 adults · 72 weeks		−20.9%−3.1%
Semaglutide 2.4 mg (Wegovy)
STEP 1 · 1,961 adults · 68 weeks		−14.9%−2.4%
Liraglutide 3.0 mg (Saxenda)
SCALE · 3,731 adults · 56 weeks		−7.4%−3.0%
Mean % change in body weight at each trial's main endpoint. The liraglutide percentages come from the Saxenda FDA label (Table 4, Study 1); the trial paper gives the number of adults and the length. Sources: Jastreboff et al., NEJM 2022 (SURMOUNT-1) (PMID 35658024); Wilding et al., NEJM 2021 (STEP 1) (PMID 33567185); Pi-Sunyer et al., NEJM 2015 (SCALE) (PMID 26132939); Saxenda FDA label, Table 4, Study 1 (DailyMed).

Newer weight-loss drugs still in testing

Change in body weight, drug vs placebo. A minus sign means weight lost

Different trials, different people: not a head-to-head comparison. None of these is FDA approved.

Show the numbers as a table
Newer weight-loss drugs still in testing: Change in body weight, drug vs placebo. A minus sign means weight lost
TrialDrugPlacebo
Retatrutide 12 mg (In testing)
TRIUMPH-1 · 2,339 adults · 80 weeks		−25.0%−3.9%
CagriSema (cagrilintide + semaglutide) (In testing)
REDEFINE 1 · 3,417 adults · 68 weeks		−20.4%−3.0%
Mazdutide 6 mg (In testing)
GLORY-1 · 610 adults in China · 48 weeks		−14.0%+0.3%
Survodutide 6.0 mg (In testing)
SYNCHRONIZE-1 · 725 adults · 76 weeks		−13.0%−5.4%
The striped bar means the placebo group gained a little weight (+0.3%). Each trial was paid for by the drug maker. Trial lengths are not the same. Sources: Jastreboff et al., NEJM 2026 (TRIUMPH-1) (PMID 42814954); Garvey et al., NEJM 2025 (REDEFINE 1) (PMID 40544433); Ji et al., NEJM 2025 (GLORY-1) (PMID 40421736); le Roux et al., NEJM 2026 (SYNCHRONIZE-1) (PMID 42253238).

Fewer heart attacks, strokes and heart deaths

% of people who had one of these, drug vs placebo, in 2 big heart trials

Different trials and different people. Lower is better.

Show the numbers as a table
Fewer heart attacks, strokes and heart deaths: % of people who had one of these, drug vs placebo, in 2 big heart trials
TrialDrugPlacebo
Semaglutide 2.4 mg (Wegovy)
SELECT · 17,604 adults with heart disease and extra weight, no diabetes · about 40 months		6.5%8.0%
Dulaglutide (Trulicity)
REWIND · 9,901 adults with type 2 diabetes		12.0%13.4%
Main result of each trial: heart attack, stroke, or death from heart causes. In SELECT, 20% fewer people had one (hazard ratio 0.80). Sources: Lincoff et al., NEJM 2023 (SELECT) (PMID 37952131); Gerstein et al., Lancet 2019 (REWIND) (PMID 31189511).

More charts: Peptides by the numbers

GLP-1 drugs vs other peptides at a glance

Wegovy / Ozempic (semaglutide)Zepbound / Mounjaro (tirzepatide)Retatrutide ("GLP-3")BPC-157
Is it a peptide?YesYesYesYes
Hormone switches1: GLP-12: GLP-1 + GIP3: GLP-1 + GIP + glucagonNot a GLP-1 drug
FDA statusApprovedApprovedIn testing, not approvedNot approved
Proof for weight loss in peopleStrongStrongSome (big trials still running)Not studied for weight
Safety dataWell studiedWell studiedLimitedVery little
Check any peptide in 1 secondFree FDA Status Checker: approved, being tested, or not proven.

FAQ

Is Ozempic a peptide?

Yes. Ozempic is semaglutide, a lab-made peptide that acts like the GLP-1 hormone.

Are peptides safer than GLP-1 drugs?

That has not been shown. Approved GLP-1 drugs have known side effects on their FDA labels. Most other peptides have so little safety data that their risks are unknown.

Can I take peptides and a GLP-1 together?

Ask your doctor first. No good studies show such mixes are safe. The FDA says the GLP-1 pill Foundayo should not be used with another GLP-1 drug.

Is compounded semaglutide the same as Ozempic?

No. Compounded versions are not FDA approved. The FDA warns that some use salt forms (semaglutide sodium or acetate), which are different ingredients.

Are collagen peptides like GLP-1 drugs?

No. Collagen peptides are sold as a supplement. They are not a GLP-1 drug and are not approved to treat obesity.

What does GLP-1 stand for?

Glucagon-like peptide-1. It is a hormone your gut makes after you eat. That is why GLP-1 drugs are called peptides: they copy a peptide hormone.

Is GLP-1 the same as Zepbound?

No. GLP-1 is a gut hormone and a group of drugs. Zepbound (tirzepatide) is one brand that acts on GLP-1 and a second hormone, GIP.

Are peptides the same as Ozempic?

No. Ozempic (semaglutide) is one FDA-approved peptide drug. Most "peptides" sold online, like BPC-157, are not GLP-1 drugs and are not FDA approved.

What is the difference between peptides and GLP-1?

"Peptides" are short chains of amino acids, a huge group. GLP-1 drugs are one kind of peptide medicine, tested in big trials and FDA approved. Compare GLP-1 prices in our GLP-1 price tracker.

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Sources

Not medical advice. Medical disclaimer.