Wegovy vs Zepbound
The Most Important Obesity Drug Comparison — Direct Trial Data from SURMOUNT-5
Wegovy (semaglutide 2.4 mg) and Zepbound (tirzepatide 15 mg) are the two leading FDA-approved obesity drugs. SURMOUNT-5 (2025) directly compared them head-to-head: tirzepatide produced approximately 47% more relative weight loss. Yet Wegovy holds stronger cardiovascular outcome data (SELECT, 2023) while Zepbound's MMO trial is ongoing. Track either in Shotlee to measure your personal results.
Mechanism of Action
- →GLP-1 receptor agonist — single incretin mechanism
- →Mimics endogenous GLP-1 released after meals
- →Suppresses appetite via hypothalamic GLP-1 receptors
- →Slows gastric emptying, prolonging satiety
- →Glucose-dependent insulin secretion enhancement
- →Half-life ~7 days; once-weekly autoinjector pen
- →SELECT trial: 20% MACE reduction in obesity + CVD (2023)
- →Dual GIP + GLP-1 receptor agonist
- →GIP receptor activation enhances adipose insulin sensitivity
- →GIP co-signalling may reduce GLP-1-driven nausea
- →Additive appetite suppression from two incretin pathways
- →Deeper weight loss vs GLP-1 monotherapy in all trials
- →Half-life ~5 days; once-weekly autoinjector pen
- →SURMOUNT-MMO cardiovascular outcomes trial ongoing
Head-to-Head Comparison
| Factor | Wegovy | Zepbound |
|---|---|---|
| Active molecule | Semaglutide | TirzepatideBest |
| Receptor targets | GLP-1 only | GIP + GLP-1 |
| FDA approval (obesity) | June 2021 | November 2023 |
| Max dose | 2.4 mg weekly | 15 mg weekly |
| Weight loss — STEP-1/SURMOUNT-1 | 14.9% (sema 2.4 mg, 68 wks) | 20.9% (tirz 15 mg, 72 wks) |
| Direct head-to-head (SURMOUNT-5) | Reference arm | ~47% more weight loss vs Wegovy |
| Nausea incidence | ~44% (STEP-1) | ~31% (SURMOUNT-1 15 mg) |
| Cardiovascular outcome trial | SELECT 2023: 20% MACE reduction | MMO trial ongoing |
| Monthly cost (uninsured) | ~$1,300–1,400 | ~$1,000–1,200 |
| T2D brand | Ozempic | Mounjaro |
Weight Loss: The Numbers
Choose Based on Your Goal
Maximum weight loss
Zepbound 15 mg achieved ~20.9% mean weight loss in SURMOUNT-1 and was directly superior to Wegovy in SURMOUNT-5.
Strongest cardiovascular evidence
Wegovy's SELECT trial (2023) showed a 20% MACE reduction in obesity + CVD. Zepbound's cardiovascular trial (MMO) is still ongoing as of 2026.
Lower nausea rates
Zepbound reported ~31% nausea in SURMOUNT-1 vs ~44% for Wegovy in STEP-1. GIP modulation may reduce GI side effects.
Cost and insurance access
Zepbound is often slightly less expensive uninsured. Both have limited insurance coverage for obesity. Check your plan's formulary.
Earlier FDA approval history
Wegovy was approved June 2021 — over two years earlier than Zepbound (November 2023). More real-world safety data is available for semaglutide.
T2D + obesity combination
Both have T2D equivalents (Ozempic/Mounjaro). Your prescriber may choose based on which indication — T2D or obesity — is primary.
Which Is Right for You?
For pure weight loss efficacy, the evidence favours Zepbound. SURMOUNT-5 (2025) is the definitive direct comparison: tirzepatide produced approximately 47% more relative weight loss than semaglutide. This is consistent with the individual trial data — SURMOUNT-1 showing 20.9% vs STEP-1's 14.9%.
Wegovy's key advantage is cardiovascular outcome data. The SELECT trial (2023) was the first obesity drug to show a statistically significant reduction in MACE (20%) in adults with obesity and established CVD — a landmark result. Zepbound's SURMOUNT-MMO cardiovascular trial is ongoing.
Tolerability: SURMOUNT-1 reported ~31% nausea rate vs ~44% for STEP-1. However, both trials used different populations and titration schedules, so direct nausea comparison should be interpreted with caution. Both drugs share the same class of GI side effects and are managed with slow dose escalation.
Wegovy vs Zepbound: Frequently Asked Questions
Zepbound. In individual trials: Zepbound 15 mg achieved ~20.9% weight loss (SURMOUNT-1) vs ~14.9% for Wegovy (STEP-1). In the 2025 SURMOUNT-5 direct head-to-head, tirzepatide produced approximately 47% more relative weight loss than semaglutide.
Currently, yes. SELECT (2023) showed a 20% MACE reduction with semaglutide 2.4 mg in people with obesity and CVD — the first obesity drug to achieve this. Zepbound's cardiovascular outcomes trial (SURMOUNT-MMO) is ongoing.
Trial data suggests Zepbound has lower nausea rates (~31% in SURMOUNT-1 vs ~44% in STEP-1 for Wegovy). Both drugs are managed with slow dose escalation to minimise GI side effects.
Yes, with prescriber guidance. No washout period is required. Start tirzepatide at 2.5 mg regardless of prior semaglutide dose and escalate normally. Track both in Shotlee so your prescriber can compare your response to each.
Both have limited obesity drug coverage. Some commercial plans, Medicare, and state Medicaid programmes cover one or both. Zepbound is often slightly less expensive without insurance. Check your specific plan formulary and manufacturer savings programmes.
Track Wegovy or Zepbound in Shotlee
Log doses, weight progress, and side effects for whichever obesity drug you use. Free for iOS and Android.
📚References & sources
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