"Which GLP-1 is best for weight loss?" is the most-asked question in the category, and it has the wrong framing. Best for what? Maximum pounds dropped? Cardiovascular protection? Kidney protection? Sleep apnea? Tolerability? Convenience? Cost? Different FDA-approved GLP-1s win on each axis — and the answer for an insured patient with diabetes is not the answer for a self-pay patient with a needle phobia.
Direct answer: For pure weight loss in 2026, tirzepatide (Zepbound) is the most effective FDA-approved drug. SURMOUNT-1 produced 20.9% mean weight loss at 15 mg over 72 weeks, and the head-to-head SURMOUNT-5 trial showed 20.2% with tirzepatide vs 13.7% with semaglutide 2.4 mg over 72 weeks. Semaglutide (Wegovy) still wins for patients who need cardiovascular protection (20% MACE reduction in SELECT) or kidney protection (24% reduction in major kidney events in FLOW). Foundayo (orforglipron) wins for pill-only users at ~12.4% mean loss in ATTAIN-1. Retatrutide — not yet approved — delivered 28.7% mean loss at 12 mg over 68 weeks in the Phase 3 TRIUMPH-4 trial. Liraglutide (Saxenda) is the oldest and weakest at ~8% over 56 weeks. The right drug depends on your goal, comorbidities, and insurance.
The FDA-Approved GLP-1 Lineup for Weight Loss (May 2026)
| Drug | Active ingredient | Route | Top dose | Pivotal trial weight loss |
|---|---|---|---|---|
| Zepbound | Tirzepatide | Weekly injection | 15 mg | 20.9% (SURMOUNT-1, 72 wk) |
| Wegovy injection | Semaglutide 2.4 mg | Weekly injection | 2.4 mg | 14.9% (STEP 1, 68 wk) |
| Wegovy HD | Semaglutide 7.2 mg | Weekly injection | 7.2 mg | ~21% (STEP UP, est.) |
| Oral Wegovy | Oral semaglutide | Daily pill | 25 mg | 13.6% (OASIS-4, 71 wk) |
| Foundayo | Orforglipron | Daily pill | 36 mg | 12.4% (ATTAIN-1, 72 wk) |
| Saxenda | Liraglutide 3 mg | Daily injection | 3 mg | 8.0% (SCALE, 56 wk) |
| Rybelsus | Oral semaglutide | Daily pill | 14 mg | 4–7 lb (diabetes label only) |
In the pipeline: retatrutide (Eli Lilly's triple GLP-1 / GIP / glucagon agonist) reported 28.7% mean weight loss at 12 mg over 68 weeks in TRIUMPH-4 — the highest figure ever reported for an anti-obesity drug in a Phase 3 trial. NDA filing is expected in Q4 2026, putting approval most likely in 2027.
Tirzepatide (Zepbound) — Strongest Pure Weight Loss
Tirzepatide is a dual GLP-1 / GIP receptor agonist. Approved by the FDA for chronic weight management in November 2023 and for moderate-to-severe obstructive sleep apnea in adults with obesity in December 2024 — the first and only OSA medication ever approved.
Key trial data
- SURMOUNT-1 (2,539 non-diabetic adults with obesity, 72 weeks): 15.0% loss at 5 mg, 19.5% at 10 mg, 20.9% at 15 mg vs 3.1% on placebo. Roughly 50–57% of patients on 10–15 mg achieved at least 20% body-weight loss.
- SURMOUNT-2 (type 2 diabetes population, 72 weeks): ~15.7% at 15 mg.
- SURMOUNT-3 (lifestyle run-in then drug, 72 weeks): up to ~26% cumulative loss.
- SURMOUNT-4 (maintenance after run-in): patients who switched to placebo regained most of the loss; tirzepatide-continuers maintained.
- SURMOUNT-OSA (Study 5/6): up to 50% of patients no longer had symptomatic OSA after 52 weeks.
Side effects
In SURMOUNT-1: nausea 31%, diarrhea 23%, vomiting 12%, constipation 11%. Treatment discontinuation due to adverse events ran roughly 6% — and importantly, in SURMOUNT-5, GI discontinuations on tirzepatide were 2.7% vs 5.6% on semaglutide, suggesting GIP signaling buffers the nausea ceiling.
Semaglutide (Wegovy) — The Outcomes Drug
Semaglutide is a pure GLP-1 receptor agonist. The injectable 2.4 mg version (Wegovy) was approved for chronic weight management in June 2021 — the trial backbone that legitimized the entire category. Wegovy has the most cardiovascular and kidney outcome data of any GLP-1.
Key trial data
- STEP 1 (1,961 non-diabetic adults, 68 weeks): 14.9% mean weight loss at 2.4 mg vs 2.4% on placebo. 50.5% of patients lost at least 15%; 32% lost at least 20%.
- STEP 2 (T2D population): ~9.6% loss — lower than non-diabetic figures, consistent with the harder weight-loss task in diabetes.
- STEP 5 (104-week extension): 15.2% maintained loss vs 2.6% placebo.
- STEP UP (semaglutide 7.2 mg, the new "Wegovy HD"): ~21% mean loss in early readouts — narrowing the gap with tirzepatide.
Outcome trial advantages (where semaglutide currently wins)
- SELECT (17,604 patients with obesity + established CVD, no diabetes): 20% reduction in major adverse cardiovascular events (CV death, non-fatal MI, non-fatal stroke). This is the basis for Wegovy's cardiovascular risk reduction indication — the only one currently on a GLP-1 label.
- FLOW (3,533 patients with T2D + CKD): 24% reduction in the composite kidney + CV death outcome, 20% reduction in all-cause mortality, slower eGFR decline. Ozempic 1 mg (same molecule) now carries a CKD indication.
- SUSTAIN-6 (T2D CV outcome trial): 26% MACE reduction.
If you have heart disease, kidney disease, or T2D + CKD, semaglutide has earned guideline-level recommendations that tirzepatide is still gathering data for (SURPASS-CVOT and SURMOUNT MMO ongoing).
Retatrutide — Highest Numbers, Not Yet Approved
Retatrutide is Lilly's next-generation triple agonist: GLP-1, GIP, and glucagon receptor activation in a single peptide. Adding glucagon raises basal metabolic rate while the GLP-1 component prevents the blood-sugar spike glucagon would otherwise cause.
Phase 3 TRIUMPH-4 (December 2025 readout)
In adults with obesity and knee osteoarthritis, 68 weeks of dosing:
- 12 mg dose: 28.7% mean weight loss (~71.2 lb)
- 9 mg dose: ~22% mean weight loss
- Placebo: ~2% loss
- Dysesthesia (abnormal skin sensation) signal at 12 mg: 20.9% vs 0.7% on placebo
- Discontinuation rates: 12.2% (9 mg) and 18.2% (12 mg) — higher than tirzepatide or semaglutide
- Common GI events: nausea 43%, diarrhea 33%, vomiting 21%
The remaining seven Phase 3 readouts (TRIUMPH-1 general obesity, TRIUMPH-2 T2D, TRIUMPH-3 CV outcomes, TRIUMPH-5 maintenance) are expected through 2026. Retatrutide is not FDA-approved as of May 2026, so prescription access is limited to clinical trials or compounding pharmacies, which carries its own regulatory ambiguity.
Foundayo (Orforglipron) — The First Non-Peptide GLP-1
Orforglipron is the first small-molecule, non-peptide GLP-1 receptor agonist. Because it isn't a peptide, stomach acid doesn't destroy it — so no SNAC absorption enhancer, no empty-stomach rule, no fasting window. Approved by the FDA in April 2026.
ATTAIN-1 Phase 3 (3,127 non-diabetic adults, 72 weeks)
- 6 mg: 7.8% weight loss
- 12 mg: 9.3% weight loss
- 36 mg: 12.4% weight loss (~27.3 lb)
- Placebo: 2.1%
- 59.6% achieved ≥10% loss at 36 mg; 39.6% achieved ≥15%
Where orforglipron wins
- No food, water, or timing rules — take it any time of day
- Room-temperature storage; travel-friendly
- For pill-only users, it edges out oral Wegovy on a head-to-head A1C basis (Lancet 2026) while running roughly even on weight at the highest comparable doses
The trade-off: ~12% pure weight loss is well below tirzepatide's ~21%, and GI discontinuation ran around 9–10% in head-to-head data with oral semaglutide.
Oral Wegovy and Rybelsus — Pill Semaglutide
Oral Wegovy (high-dose oral semaglutide, approved January 2025) drives 13.6% mean weight loss at 25 mg over 71 weeks — close to the injectable's 14.9%. The catch is the strict morning fasting rule: take with no more than 4 oz of water, wait 30 minutes before food, drink, or other oral meds. Patients on levothyroxine, omeprazole, or warfarin have to time their morning carefully.
Rybelsus is the original 2019 oral semaglutide product. The dose tops out at 14 mg — too low for serious weight-loss numbers (typically 4–7 lb at 6 months). It is approved only for type 2 diabetes.
Liraglutide (Saxenda) — Daily, Older, Smaller Loss
Liraglutide 3 mg is the oldest GLP-1 weight-loss drug — approved in 2014. The SCALE Obesity and Prediabetes trial showed 8.0% mean weight loss at 56 weeks vs 2.6% on placebo. Daily injection, no weekly dosing, smaller numbers across the board. Saxenda has been overtaken by Wegovy in real-world prescriptions.
Its main remaining role: adolescent weight management (approved 12+) and as a stepping-stone in regions where weekly drugs aren't covered. Generic liraglutide is now available in some markets, which has driven the cost down.
The SURMOUNT-5 Head-to-Head
SURMOUNT-5 is the only proper head-to-head trial comparing maximum tolerated doses of tirzepatide and semaglutide for obesity. Reported December 2024, full publication NEJM May 2025.
| Endpoint at 72 weeks | Tirzepatide (10/15 mg) | Semaglutide (1.7/2.4 mg) |
|---|---|---|
| Mean weight loss | −20.2% (~22.8 kg) | −13.7% (~15.0 kg) |
| Waist circumference reduction | −18.4 cm | −13.0 cm |
| ≥25% body-weight loss | 31.6% | 16.1% |
| GI-related discontinuation | 2.7% | 5.6% |
Tirzepatide hit the primary endpoint and all five key secondary endpoints. The roughly 6.5-percentage-point gap is the cleanest, most-cited number anyone can offer on the question of "which is more effective for pure weight loss."
Decision Matrix: Which Drug Wins on Each Goal
| If your priority is… | Best GLP-1 in 2026 |
|---|---|
| Maximum pure weight loss | Tirzepatide (Zepbound) 15 mg, or Wegovy HD 7.2 mg |
| Cardiovascular event reduction | Semaglutide (Wegovy/Ozempic) — only one with a CVOT indication |
| Kidney protection in T2D + CKD | Semaglutide — Ozempic 1 mg carries the CKD indication |
| Obstructive sleep apnea (moderate–severe) | Tirzepatide (Zepbound) — only OSA-indicated drug |
| Pill-only, no food rules | Foundayo (orforglipron) |
| Pill, maximum loss | Oral Wegovy 25 mg |
| Lowest GI side-effect rate at high doses | Tirzepatide (lower discontinuation in SURMOUNT-5) |
| Adolescent (12–17) weight management | Liraglutide (Saxenda) or semaglutide 2.4 mg |
| Cheapest in-market self-pay starting dose | Wegovy starter pen ($199 first 2 months) or oral Wegovy 4 mg ($149) |
| Insurance + savings card | Either Wegovy or Zepbound at $25/month if commercially insured |
| Highest weight loss in trials (not yet approved) | Retatrutide 12 mg (28.7%) — wait for FDA approval |
Cost Comparison (May 2026, US)
| Drug | List price/month | Self-pay (Lilly/Novo direct) | With manufacturer savings card |
|---|---|---|---|
| Zepbound 2.5 mg pen | ~$1,086 | $299 | as low as $25 |
| Zepbound 5–15 mg pen | ~$1,086 | $399–$449 | as low as $25 |
| Wegovy 0.25/0.5 mg starter | ~$1,349 | $199 (first 2 months) | as low as $25 |
| Wegovy 1.0–2.4 mg | ~$1,349 | $349 | as low as $25 |
| Wegovy HD 7.2 mg | ~$1,349 | $399 | as low as $25 |
| Oral Wegovy 1.5/4 mg | ~$1,349 | $149 (4 mg, through Aug 2026) | as low as $25 |
| Oral Wegovy 9/25 mg | ~$1,349 | $299 | as low as $25 |
| Foundayo (orforglipron) | ~$1,300 | ~$149 starting | ~$25 with commercial insurance |
| Saxenda | ~$1,349 | $549 | varies |
| Rybelsus | ~$1,027 | not widely cash-priced | $25 for commercially insured |
Medicare Part D still does not cover GLP-1s for the obesity indication. Diabetes use (Ozempic, Mounjaro, Rybelsus) is reimbursed much more reliably than obesity use (Wegovy, Zepbound, Foundayo).
Side Effect Discontinuation: The Real-World Question
In trials, treatment discontinuation due to adverse events runs:
| Drug | GI-related discontinuation |
|---|---|
| Tirzepatide 10–15 mg | 2.7–6% |
| Semaglutide 2.4 mg | 5.6–7% |
| Oral semaglutide 25 mg | ~7% |
| Orforglipron 36 mg | ~9–10% |
| Retatrutide 12 mg | ~18% |
| Liraglutide 3 mg | 9–10% |
GIP receptor activation appears to buffer GLP-1-driven nausea, which is why tirzepatide tolerates higher relative doses than pure GLP-1 agonists. Retatrutide's higher number probably reflects both the glucagon component and the steep dose curve.
Real-world adherence numbers are worse than trial numbers. Roughly half of patients discontinue within a year in commercial-claims data, mostly from side effects, cost, and supply problems — not from lost benefit.
What People Get Wrong About "Which Is Best"
- "More weight loss = better drug." Not if you have coronary artery disease without diabetes — SELECT is on semaglutide's label, not tirzepatide's. The cardiovascular community defaults to semaglutide for CVD-comorbid obesity until the SURPASS-CVOT readout (expected 2026).
- "Retatrutide is available now." It is in Phase 3 trials and is not FDA-approved. Compounded retatrutide exists in a regulatory gray area and is not the same product Lilly is testing.
- "Tirzepatide is just a stronger GLP-1." Tirzepatide's GLP-1 receptor binding is actually weaker than semaglutide. The added GIP activity and biased β-arrestin signaling are what produce its weight-loss advantage.
- "Pills are gentler." Oral semaglutide actually shows slightly higher GI rates than the injectable at top dose, because the daily peak concentration is higher.
- "All GLP-1s help with OSA." Only tirzepatide carries an OSA indication. Other drugs may help by virtue of weight loss but aren't on-label.
- "Once you stop, you keep the weight off." STEP 1 extension and SURMOUNT-4 both show ~two-thirds of weight loss is regained within a year of stopping. These are long-term medications.
Frequently Asked Questions
Which GLP-1 produces the most weight loss? Among FDA-approved drugs, tirzepatide (Zepbound) at 15 mg — about 20.9% over 72 weeks in SURMOUNT-1, and 20.2% in the head-to-head SURMOUNT-5 vs semaglutide's 13.7%. Retatrutide in Phase 3 trials produced 28.7% at 12 mg over 68 weeks but is not yet approved.
Is Ozempic or Wegovy better for weight loss? They are the same molecule (semaglutide). Wegovy doses up to 2.4 mg weekly and is FDA-approved for weight management. Ozempic doses up to 2.0 mg and is approved for diabetes — weight loss is a secondary effect.
Is tirzepatide better than semaglutide? For pure weight loss and waist reduction, yes — SURMOUNT-5 showed a 6.5-percentage-point advantage at 72 weeks. For cardiovascular and kidney outcomes, semaglutide has more guideline-level data.
Is Zepbound better than Wegovy? SURMOUNT-5 showed Zepbound (tirzepatide 10/15 mg) produced more weight loss than Wegovy (semaglutide 1.7/2.4 mg) — 20.2% vs 13.7% over 72 weeks. Wegovy HD at 7.2 mg, approved in 2025, narrows this gap.
What is the best GLP-1 pill for weight loss? For maximum loss, oral Wegovy at 25 mg (13.6%). For convenience without food rules, Foundayo (orforglipron) at 36 mg (~12.4%). Both are far below injectable tirzepatide.
Which GLP-1 is best for people with heart disease? Semaglutide (Wegovy 2.4 mg or Ozempic 1.0–2.0 mg). The SELECT trial showed a 20% reduction in major adverse cardiovascular events — a benefit only semaglutide currently carries on its label.
Which GLP-1 is best for diabetes with kidney disease? Semaglutide. The FLOW trial showed a 24% reduction in major kidney events and 20% reduction in all-cause mortality. Ozempic 1 mg now has a CKD indication.
Which GLP-1 has the fewest side effects? At the relative doses studied head-to-head, tirzepatide had the lowest GI-related discontinuation (2.7% in SURMOUNT-5). Liraglutide has the smallest weight-loss footprint but also the longest real-world side-effect history.
Is retatrutide available now? No. Retatrutide is in Phase 3 trials. Lilly is expected to file an NDA in late 2026, so approval is most likely in 2027.
Last reviewed: May 13, 2026
Sources
- Tirzepatide as Compared with Semaglutide for the Treatment of Obesity (SURMOUNT-5) — NEJM/PubMed
- SURMOUNT-5: Greater Weight Loss with Tirzepatide than Semaglutide — American College of Cardiology
- Lilly: tirzepatide superior to Wegovy in head-to-head trial, 20.2% vs 13.7%
- Once-Weekly Semaglutide in Adults with Overweight or Obesity (STEP 1) — NEJM
- Semaglutide and Cardiovascular Outcomes in Obesity without Diabetes (SELECT) — NEJM
- Effects of Semaglutide on Chronic Kidney Disease in Patients with Type 2 Diabetes (FLOW) — NEJM
- FDA Approves First Medication for Obstructive Sleep Apnea (tirzepatide) — FDA
- Orforglipron, an Oral Small-Molecule GLP-1 Receptor Agonist for Obesity Treatment — NEJM
- Oral GLP-1 Drug Orforglipron Promotes Substantial Weight Loss — Cornell Chronicle
- Retatrutide TRIUMPH-4: 28.7% Weight Loss, Triple Trial Triumph — BioSpace
- A Randomized, Controlled Trial of 3.0 mg of Liraglutide in Weight Management (SCALE) — NEJM
- Comparing Ozempic, Wegovy and Other GLP-1 Drugs — GoodRx
- Wegovy 2026 Prices, Coupons & Savings Tips — GoodRx
- Zepbound 2026 Prices, Coupons & Savings Tips — GoodRx
