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Weight loss

Tirzepatide

A prescription GIP/GLP-1 medicine that produced substantial, sustained weight loss in a large phase 3 obesity trial.

Strong
Evidence rating
Evidence review

What the evidence says

Tirzepatide activates GIP and GLP-1 receptors and is prescribed for chronic weight management in eligible patients. SURMOUNT-1 randomized 2,539 adults with obesity or overweight plus a related complication, without diabetes, to three tirzepatide doses or placebo for 72 weeks.[1]

Average weight change at 72 weeks ranged from 15.0% to 20.9% across tirzepatide doses, compared with 3.1% for placebo. Most participants receiving tirzepatide lost at least 5% of baseline weight, and prespecified cardiometabolic measures also improved.[1]

SURMOUNT-3 found additional weight loss when tirzepatide followed a 12-week intensive lifestyle program. SURMOUNT-4 then showed the importance of continued therapy: people switched to placebo after a tirzepatide lead-in regained substantial weight, while continued treatment maintained and extended the loss.[3][4]

In participants with obesity and prediabetes, three years of treatment sustained weight loss and markedly reduced progression to type 2 diabetes during treatment. This result applies to that selected high-risk group and does not establish a general anti-aging effect.[5]

This is strong evidence for obesity treatment rather than a direct longevity claim. Tirzepatide is a prescription medicine with dose escalation, contraindications, adverse-effect management, and decisions about long-term treatment that belong in clinical care.[2]

Potential benefits

  • Produces substantial average weight loss across studied maintenance doses.[1]
  • Improves multiple cardiometabolic measures in parallel with weight reduction.[1]

Side effects and cautions

  • Nausea, diarrhea, vomiting, constipation, abdominal pain, and other gastrointestinal effects are common, particularly during dose escalation.[1][2]
  • The label includes contraindications and warnings involving thyroid C-cell tumor risk language, severe gastrointestinal reactions, gallbladder disease, pancreatitis, hypersensitivity, and kidney injury from volume depletion.[2]
How we scored it

Evidence breakdown

Large randomized trials show clinically meaningful weight loss across approved doses, with safety and monitoring requirements defined in product labeling.

Clinical relevanceHigh

The primary outcomes are sustained percentage weight loss and responder thresholds.

Study qualityHigh

Evidence includes a large, double-blind, randomized phase 3 trial.

Safety dataHigh

Common adverse effects and serious precautions are covered by prescribing guidance.

References

Full source list

  1. Tirzepatide Once Weekly for the Treatment of Obesity

    The New England Journal of Medicine · 2022

  2. Zepbound (tirzepatide) prescribing information

    DailyMed, U.S. National Library of Medicine · 2026

  3. Tirzepatide after intensive lifestyle intervention in adults with overweight or obesity: the SURMOUNT-3 phase 3 trial

    Nature Medicine · 2023

  4. Continued Treatment With Tirzepatide for Maintenance of Weight Reduction in Adults With Obesity: The SURMOUNT-4 Randomized Clinical Trial

    JAMA · 2024

  5. Tirzepatide for Obesity Treatment and Diabetes Prevention

    The New England Journal of Medicine · 2024