Wegovy vs Ozempic vs Mounjaro: Which Results in the Best Weight Loss?

Wegovy, Ozempic and Mounjaro: Which Weight Loss Injection Is Right for You?

In recent years, injectable medications for weight loss have gained enormous popularity. From celebrity endorsements to NHS pilot schemes, medications like Wegovy, Ozempic and Mounjaro have become common talking points in the UK. But with so many names—and even more hype—it’s easy to feel overwhelmed when trying to understand what they are, how they work, and whether they’re right for you.

This blog offers a clear, practical comparison of the three main injectable medications used for weight loss: Wegovy (semaglutide), Ozempic (semaglutide), and Mounjaro (tirzepatide). We'll explore how they work, how much weight people typically lose on them, common side effects, and frequently asked questions, so you can make an informed decision.

How They Work

All three medications help regulate appetite by mimicking hormones that affect blood sugar and feelings of fullness. Wegovy and Ozempic both contain semaglutide, which mimics the GLP-1 hormone. Mounjaro contains tirzepatide, which mimics both GLP-1 and another hormone called GIP, offering a dual-action approach.

These hormones slow digestion, reduce appetite, and help regulate insulin levels, making you feel fuller for longer and less likely to overeat. Mounjaro’s additional mechanism is believed to enhance its effectiveness compared to semaglutide-based treatments.

How Much Weight Can You Lose?

Clinical trials have shown significant differences in the level of weight loss achieved across the three medications.

Wegovy users lost, on average, about 14.9% of their body weight over 68 weeks in clinical trials. In comparison, Mounjaro users saw an average weight loss of up to 22% over 72 weeks, making it the most effective weight loss injection on the market today. Ozempic, which was originally developed for managing type 2 diabetes rather than weight loss, generally results in weight loss of around 10–15% of body weight, depending on the dose and the individual's circumstances.

It’s important to note that while these figures are averages from controlled clinical settings, real-world results vary. Weight loss may be lower for people who don’t make accompanying lifestyle changes, or who experience difficulties with side effects or adherence.

Side Effects to Be Aware Of

The most commonly reported side effects across all three medications include nausea, vomiting, constipation, diarrhoea, and stomach discomfort. These symptoms tend to occur most frequently when starting treatment or increasing the dose, and often settle over time.

In rare cases, more serious issues such as pancreatitis or gallbladder problems have been reported, which is why all of these medications should only be used under medical supervision. There have also been anecdotal reports of hair thinning, fatigue, and muscle loss, especially if weight is lost too rapidly.

An important point for many patients to consider is that weight is often regained when the medication is stopped—especially if lifestyle changes aren't maintained during and after treatment. Support around nutrition, mindset and movement is key to long-term success.

Mounjaro vs Wegovy vs Ozempic: A Quick Comparison