How does Mounjaro compare to other weight-loss medications?

 Most other weight-loss injections, like semaglutide (used in Wegovy), act only on the GLP-1 receptor. Mounjaro’s dual action on GIP and GLP-1 sets it apart, giving it a broader effect on metabolism and appetite regulation. Clinical studies suggest this combination may lead to greater improvements in blood sugar and weight, though results vary from person to person.

Understanding the difference in how they work

Both Mounjaro and Wegovy belong to a class of medicines known as incretin-based therapies. They mimic gut hormones that help regulate insulin, appetite, and digestion. However, Wegovy (semaglutide) works only through the GLP-1 receptor, while Mounjaro (tirzepatide) activates both GLP-1 and GIP receptors. NICE’s 2025 guidance calls this “dual-agonist action,” the first of its kind approved in the UK. By engaging an additional hormonal pathway, Mounjaro appears to have a stronger impact on how the body handles glucose and stores energy. NHS clinical summaries explain that this mechanism can help sustain weight loss while supporting healthy blood-sugar levels in people with or without type 2 diabetes.

Comparing clinical results

In major phase-3 trials submitted to NICE, tirzepatide users achieved average body-weight reductions of around 20 – 22 percent, compared with 15 percent typically seen in semaglutide studies. The Lancet Diabetes & Endocrinology reported that these outcomes held even in adults without diabetes, indicating a direct effect on metabolism rather than glucose correction alone. It’s important to note that the two drugs haven’t been tested head-to-head in the same population at UK-licensed doses. NICE emphasises that individual response varies, and factors such as starting weight, dose escalation, and lifestyle play a role. Some people find their rhythm improves if they keep regular mealtimes and gentle physical activity during treatment, helping stabilise energy levels as their metabolism adjusts.

Side-effect patterns and tolerability

Both medicines can cause similar early symptoms such as nausea, mild bloating, or reduced appetite. NICE and MHRA updates highlight that these effects usually ease with time and are lessened by slow dose titration. A number of people have noticed that it’s easier if they eat slowly and avoid very rich foods during the first few weeks. NHS clinics often suggest spacing out high-fat meals and focusing on hydration. Some emerging evidence hints that GIP stimulation in Mounjaro may moderate some of the gastrointestinal discomfort associated with GLP-1-only drugs, though findings are still being explored.

Availability and eligibility in the UK

NICE recommends Wegovy (semaglutide) for people with a body-mass index (BMI) ≥ 35 kg/m² or ≥ 30 kg/m² with weight-related conditions. Mounjaro (tirzepatide) received NICE approval in 2025 under TA1026 for adults with obesity who meet similar criteria but have either not responded adequately to other treatments or have concurrent type 2 diabetes. Both are available only under specialist supervision and require ongoing lifestyle support through NHS weight-management pathways. Some individuals prefer to start treatment within a multidisciplinary programme that includes dietetic and psychological support, which NHS England funding guidance recognises as best practice.

Broader metabolic effects

Beyond weight reduction, tirzepatide’s dual-pathway activity improves multiple metabolic markers. Studies published in JAMA Network Open and Nature Medicine show consistent improvements in HbA1c, blood pressure, and cholesterol, alongside significant reductions in liver-fat content. Semaglutide also produces benefits in these areas, but the magnitude appears slightly smaller on average. People who keep going with treatment say they benefit from understanding that these metabolic shifts often develop gradually over months. Regular check-ups help ensure that results are monitored safely and that expectations remain realistic.

Choosing between medicines

Clinicians decide between Mounjaro and Wegovy based on medical history, treatment goals, and tolerance. Some people may respond better to one drug’s appetite-suppressing effects, while others prefer the steadier digestion pattern seen with tirzepatide. NHS specialists typically start at the lowest dose and build up slowly to balance results with comfort. In practice, many people manage better by setting small, achievable lifestyle targets alongside their medication. A routine that works for many is to plan weekly injections on the same day, track food intake briefly, and discuss progress at follow-up appointments. These habits help sustain motivation and reinforce that medication is one part of a broader plan.

The bigger picture

Mounjaro’s main distinction lies in its dual-receptor design, giving it a wider metabolic reach than single-pathway drugs such as Wegovy. Early evidence suggests that this approach may translate into greater average weight loss and stronger improvements in blood-sugar control, though both medicines have proven benefits when used correctly within NHS guidelines.