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Healthcare GLP-1 / Obesity

GLP-1 Efficacy — Semaglutide vs Tirzepatide in Trials

Published:
Jun 15, 2026
Updated:
Jun 14, 2026
Last reviewed:
Jun 15, 2026

Research question

How do approved GLP-1 medications compare on mean body-weight reduction in their pivotal trials?

Short answer

Tirzepatide 15mg produced the largest trial-mean weight reduction (−20.9%) vs semaglutide 2.4mg at −14.9% and liraglutide 3.0mg at −7.4%.

Source: FDA Drug Labels

Key findings

  • Tirzepatide produced the largest mean body-weight reduction (−20.9%) in head-to-head trials
  • Semaglutide remains the most widely prescribed GLP-1 (Wegovy / Ozempic), ~52% manufacturer share
  • Outcomes are trial means — individual response varies and medication is one input alongside diet and activity

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# GLP-1 Efficacy — Semaglutide vs Tirzepatide in Trials

## Research Question
## Short Answer
## Key Findings
## Data Table
## How To Use This With AI
## Suggested Prompts
## Sources
## Caveats

Data table

GLP-1 Efficacy — Semaglutide vs Tirzepatide in Trials — data table
drug body_weight_reduction_pct
Semaglutide 2.4mg (Wegovy) 14.9
Tirzepatide 15mg (Zepbound) 20.9
Liraglutide 3.0mg (Saxenda) 7.4
Placebo (pooled) 2.4

Analysis

In the pivotal STEP (semaglutide) and SURMOUNT (tirzepatide) programmes, the dual GIP/GLP-1 agonist tirzepatide produced larger mean weight reduction than semaglutide at its highest dose, while liraglutide (older single agonist, daily injection) trailed both substantially. Novo Nordisk's ~52% market share reflects semaglutide's earlier launch and broader payer coverage rather than relative efficacy. These are population means from controlled trials; real-world adherence, side effects, and dose titration meaningfully shift individual outcomes.

How to use this with AI

Use this context file to start a research conversation with an AI tool. It includes the key findings, chart data, sources, and caveats so the model starts from structured context instead of a blank prompt.

Use cases

  • Brief a benefits team on relative efficacy when designing a GLP-1 coverage policy.
  • Inform a payer prior-authorization framework with trial-mean efficacy benchmarks.
  • Build a market-sizing analysis tying efficacy to addressable population for obesity drugs.

Suggested prompts

  • Using this Deepstory context on GLP-1 trial efficacy, summarize the trade-offs a self-insured employer should consider when adding GLP-1 coverage to a health plan.
  • Build a one-page brief comparing the pivotal trial designs of STEP and SURMOUNT to explain why head-to-head comparison should be done carefully.

Sources

Source quality:
Primary source
Last reviewed:
Jun 15, 2026

Caveats

  • This is health-information context, not medical advice — clinical decisions require a qualified clinician.
  • Values shown are trial population means; individual responses vary significantly and many patients discontinue due to GI side effects.
  • Efficacy values: semaglutide and tirzepatide from the brief (STEP / SURMOUNT programmes via ClinicalTrials.gov); liraglutide 3.0mg from the FDA Saxenda label; placebo from pooled trial arms.

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#glp1 #semaglutide #tirzepatide #obesity #clinical-trials