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ObesityJuly 2022

What the SURMOUNT-1 Trial Found — Tirzepatide for Weight Loss in Obesity

SURMOUNT-1 tested tirzepatide, a weekly injection that activates two gut hormones (GLP-1 and GIP) instead of just one, in 2,539 adults with overweight or obesity but without diabetes. Over 72 weeks, the highest dose produced an average ~22.5% body weight loss — the largest effect ever shown in a weight-loss medication trial.

What the trial was testing

The SURMOUNT-1 enrolled 2,539 patients with obesity. The study was sponsored by Eli Lilly and Company and tracked outcomes across the full group of patients who matched the trial's eligibility profile.

It was a large trial designed to confirm whether the treatment works well enough for wider use. Trials at this stage are designed to produce evidence regulators and physicians can act on — not just observations to follow up later.

What the results showed

~22.5% average body weight loss on the highest tirzepatide dose at 72 weeks.

New England Journal of Medicine · 2022 · NCT04184622

These findings — that average body weight loss on highest-dose weekly tirzepatide vs. placebo at 72 weeks — were published in the New England Journal of Medicine and represent the headline result of the study.

Researchers tracked outcomes across 2,539 patients enrolled in the trial. The result was consistent enough across the group that the team felt confident reporting it.

What this means for patients

For patients with obesity, this result changes the calculus on what to ask their care team about. Whether it changes day-to-day care depends on factors like disease subtype, prior treatments, and where the patient is in their care journey.

What you can do now

Tirzepatide is FDA-approved for obesity as Zepbound (Eli Lilly) and for diabetes as Mounjaro, available now. Both Wegovy (semaglutide) and Zepbound (tirzepatide) are options; SURMOUNT-1 showed larger average weight loss with Zepbound. Coverage and price vary widely; supply has been a real issue. Ask your doctor about eligibility, and check Lilly's direct-purchase program if your insurance won't cover it.

Eligibility for the treatments mentioned above depends on specific test results and clinical history. Bring this summary, the trial name, and your most recent labs or pathology report to your next visit.