SURMOUNT-OSA: what weight loss percentage did tirzepatide achieve?

Step 1: understand what SURMOUNT-OSA actually tested

The SURMOUNT programme ran multiple large clinical trials across different populations. SURMOUNT-OSA was specifically designed for adults who had both obesity and moderate-to-severe obstructive sleep apnoea, a condition where the airway repeatedly narrows or closes during sleep, disrupting breathing and causing fragmented rest. That distinction is important because many people searching this topic want to know whether tirzepatide addresses the sleep-related problem, not just the weight.

Participants were split into two cohorts: those not using positive airway pressure (PAP) therapy and those who were. Across both groups, tirzepatide at the highest tolerated dose produced approximately 18–20% average weight reduction over 52 weeks compared with placebo, figures that sit within the broader range of tirzepatide weight loss percentages recorded across its clinical trial programme. Crucially, the trial also measured the apnoea-hypopnoea index, which counts breathing disruptions per hour of sleep. Tirzepatide produced a clinically significant reduction in AHI alongside the weight change, a finding reported in the New England Journal of Medicine's broader semaglutide and GLP-1 literature, with tirzepatide's own sleep apnoea data published in the same journal in 2024.

The mechanism is straightforward in principle: reduced upper-body adiposity lessens the physical load on the airway. Less tissue, less collapse. Whether that translates to reduced PAP reliance depends on the individual and is a question for a clinical discussion, not a trial average.

Step 2: place these results alongside SURMOUNT-1 to see the full picture

SURMOUNT-OSA's weight-loss percentages sit slightly below the headline figures from SURMOUNT-1, where 2,539 adults without diabetes reached an average body-weight reduction of around 20–21% at the 15mg dose over 72 weeks. The difference reflects the study design: SURMOUNT-OSA ran for 52 weeks, not 72, and enrolled a population selected for a specific comorbidity rather than obesity alone.

For a fuller breakdown of how each SURMOUNT trial was designed and what each result means, the SURMOUNT programme overview on this site walks through the key studies side by side. The short version: SURMOUNT-OSA confirms that the weight-loss effect holds in people with a common and serious obesity-related condition, and that the benefit extends beyond the scales.

It's also worth noting that SURMOUNT-5 (a head-to-head trial against semaglutide 2.4mg) reported greater average weight loss with tirzepatide over 72 weeks, results that are part of the tirzepatide weight loss percentages seen across the full SURMOUNT trial series. SURMOUNT-OSA adds a further dimension to that picture by showing the medicine works across a clinically important sub-group.

Step 3: connect the trial results to UK eligibility and private access

Under UK private prescribing criteria, tirzepatide (sold as Mounjaro) is licensed for adults with a BMI of 30 or above, or 27 or above if at least one weight-related condition is present. Obstructive sleep apnoea is explicitly recognised as such a condition. That means someone with a BMI of, say, 28 and diagnosed sleep apnoea could meet the clinical criteria, though the prescriber assesses the whole picture, not just the numbers. If you want to understand what typical outcomes look like for Mounjaro users, our page on Mounjaro weight loss percentage sets out the figures in plain terms.

NICE's appraisal of tirzepatide, TA1026 published December 2024, sets NHS eligibility at a BMI of 35 or above with at least one qualifying comorbidity (thresholds are 2.5 kg/m² lower for some ethnic backgrounds). NHS access is phased and still being rolled out, which is why many people explore the private route in the meantime.

If you're thinking about the cost side, our Mounjaro price comparison page sets out what to expect from private providers and what a legitimate price actually includes. Worth a read before you start comparing quotes.

Treatment begins at the 2.5mg starting dose, a pen designed to let your body adjust, not to deliver the full therapeutic effect from week one. The prescriber titrates from there, typically in four-week steps, working toward the dose that balances results with tolerability for you specifically. Dosing decisions are always made by the prescriber, not the patient.

Step 4: know what to watch for and when to get medical help

The side-effect profile in SURMOUNT-OSA mirrored the broader programme: gastrointestinal symptoms dominated, chiefly nausea, loose stools, and occasional vomiting, most noticeable after starting or after a dose increase and generally settling over days to a couple of weeks. The NHS tirzepatide medicine page lists these clearly and is worth bookmarking before you start treatment.

One signal that warrants prompt medical attention is severe stomach pain that reaches the back, possibly with vomiting. The MHRA highlighted acute pancreatitis as an infrequent but serious known risk with GLP-1 medicines in a January 2026 Drug Safety Update; if that symptom pattern appears, seek urgent help rather than waiting for your next check-in. Gallbladder symptoms, signs of dehydration from prolonged GI illness, or any allergic reaction are also reasons to contact a healthcare professional quickly. Reporting suspected side effects via the MHRA Yellow Card scheme helps the regulator build a clearer picture for everyone.

Tirzepatide is not recommended during pregnancy, while breastfeeding, or for anyone trying to conceive. It is not licensed for under-18s. Anyone with a history of medullary thyroid carcinoma or MEN2 should not use it. These are conversations a prescriber leads, which is exactly why every order at nume is reviewed by a GPhC-registered Independent Prescriber before anything is dispensed. If questions come up between doses, our support team is available seven days a week.

If you'd like to explore whether tirzepatide could be appropriate for your situation, the free consultation with our clinical team is the right first step. Orders placed before noon on a weekday (even Monday morning after a bank holiday weekend) go through same-day clinical review and, once approved, are dispatched the same day for free next-working-day DPD delivery.

Start your free consultation and one of our prescribers will assess your full picture, including any conditions like sleep apnoea that may be relevant to both eligibility and expected outcomes.