Ozempic 8-week weight loss results — and how Mounjaro compares

What Ozempic's early results look like, and why it isn't licensed for this

Ozempic contains semaglutide at doses up to 2mg, approved in the UK by the MHRA for blood-sugar control in type 2 diabetes. It is not licensed for weight management, and the NHS medicines page for semaglutide is clear on this point. People sometimes share "before and after" photos from an Ozempic course because the medicine does suppress appetite, but using it outside its licence, without the clinical oversight a weight-management programme provides, carries real risks and bypasses the escalating-dose safety net that exists for a reason.

At the eight-week mark under any semaglutide regimen, the dose is typically still 0.5mg or at most 1mg, well below the 2.4mg maintenance dose used in weight-loss trials. A reasonable expectation at that point is around 2–4% body weight reduction, depending on starting point, diet and activity. The dramatic results from "before and after" posts online almost always represent much longer periods, or higher doses, or both. That context rarely travels with the photograph.

If you're interested in semaglutide for weight loss, the licensed product is Wegovy. Our page on Wegovy versus Mounjaro covers how the two medicines compare across the full treatment period.

How Mounjaro's eight-week results fit into a longer picture

Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist (the only medicine of its kind licensed for weight management in the UK) made by Eli Lilly. Its titration schedule starts at 2.5mg, a dose designed to let your body adjust, not to produce rapid weight loss. Most people move to 5mg at around week five. By week eight, they are typically a few weeks into their first therapeutic dose.

In the SURMOUNT-1 trial, published in the New England Journal of Medicine, participants on tirzepatide 15mg lost an average of around 20–21% of body weight over 72 weeks. The weight loss was not front-loaded: the curve is gradual and continues well past the initial months. Expecting to judge the medicine's potential from an eight-week snapshot is a bit like appraising a long-haul flight from the first twenty minutes of cruising altitude.

One practical habit worth building early: weigh yourself on the same day, at the same time, before eating or drinking. A single weekly reading is more useful than daily fluctuations. It gives you and your prescriber a clean trend line to review, and reviewing it honestly is how dose adjustments get made well.

Head-to-head: what the direct comparison data show

The SURMOUNT-5 trial, published in the New England Journal of Medicine in 2025, was the first rigorous head-to-head study comparing tirzepatide directly against semaglutide 2.4mg in adults with obesity but without type 2 diabetes. Over 72 weeks, tirzepatide produced greater average weight reduction. NICE's appraisal of tirzepatide (TA1026) also noted, in its committee discussion, that indirect comparisons favour tirzepatide over semaglutide 2.4mg.

The gap narrows with the newer Wegovy 7.2mg dose (trials reported around 20.7% average loss at that strength) and the MHRA approved a dedicated single-dose 7.2mg pen in April 2026. So the landscape is genuinely moving. A comparison drawn from data available eighteen months ago looks different today.

Which of the two licensed medicines suits you depends on your health history, what other medicines you take and how your body responds, factors a prescriber works through with you. You can read more about how weight loss on Wegovy compares to Mounjaro across the full treatment arc.

What is licensed for weight loss in the UK, and how to access it properly

The two medicines licensed in the UK for weight management in adults are Mounjaro (tirzepatide) and Wegovy (semaglutide injection), alongside the newer Wegovy tablet, which received MHRA approval in June 2026 as the first oral GLP-1 medicine for weight management in the UK. Ozempic is not on that list. Using Ozempic for weight loss means using a medicine outside its licensed indication, typically obtained without the clinical assessment that identifies whether it is safe for you specifically.

Both Mounjaro and Wegovy are prescription-only medicines. A prescriber (not a checkout page) decides whether either is clinically appropriate after reviewing your health history, current medicines and BMI. At nume, that review is carried out by a GPhC-registered Independent Prescriber, the same day you submit your consultation. If you're still deciding between the two options, our prescribers can help you think through what the evidence means for your situation. You can also explore our overview of weight-loss treatments to see what's available before you book.

If you've already been on one medicine and are considering switching, there are specific clinical considerations, including how long after Mounjaro you can start Wegovy and what to do if you find Wegovy is not working as expected after Mounjaro, our pages on switching from Ozempic to Mounjaro and on what happens to weight after stopping treatment cover the questions we hear most often. Which medicine suits you is a clinical decision our prescribers make with you.