Health Benefits of Mounjaro and Wegovy Beyond Weight Loss: What the Evidence Shows

Blood sugar and type 2 diabetes

This is where both medicines began. In the SURPASS programme, tirzepatide lowered HbA1c by around 2 percentage points on average, more than any comparator including insulin and injectable semaglutide, and a high proportion of participants reached non-diabetic HbA1c levels. Semaglutide’s SUSTAIN trials showed reductions of around 1.5 points. For people with prediabetes, the three-year SURMOUNT-1 extension found that tirzepatide cut progression to type 2 diabetes by more than 90% compared with placebo while treatment continued.

One consequence matters for anyone already on diabetes medicines: because these medicines improve insulin response, the dose of insulin or a sulphonylurea often needs reducing to avoid low blood sugar. That is a conversation for your diabetes team before you start.

Heart and blood vessels

The clearest evidence is for semaglutide. The SELECT trial followed more than 17,000 adults with established cardiovascular disease and a BMI of 27 or more, without diabetes, for over three years. Those on semaglutide 2.4 mg had 20% fewer heart attacks, strokes and cardiovascular deaths than those on placebo. On the strength of that, Wegovy’s UK licence now includes reducing cardiovascular risk in that group, and NICE has appraised it for NHS use on that basis.

Tirzepatide’s equivalent outcome trial, SURPASS-CVOT, compared it against another GLP-1 medicine (dulaglutide) in people with type 2 diabetes and heart disease and reported non-inferiority with a numerical advantage, but a placebo-controlled trial in people without diabetes (SURMOUNT-MMO) is still running. Both medicines consistently lower systolic blood pressure by around 5 to 8 mmHg and improve cholesterol and triglyceride levels in weight-management trials, effects that track closely with the amount of weight lost. Semaglutide has also shown symptom and functional improvements in heart failure with preserved ejection fraction (STEP-HFpEF).

Obstructive sleep apnoea

The two SURMOUNT-OSA trials tested tirzepatide in adults with obesity and moderate to severe sleep apnoea, with and without CPAP. After a year the number of breathing interruptions per hour fell by roughly 25 to 30 events, about a 50 to 60% reduction, compared with small changes on placebo, and a meaningful share of participants no longer met the threshold for treatment. Sleep apnoea is one of the licence-listed conditions that can make someone eligible for treatment at a BMI of 27 rather than 30, and this is the evidence behind that.

Liver fat and MASH

Metabolic dysfunction-associated steatotic liver disease (previously called non-alcoholic fatty liver disease) is common in obesity, and its inflammatory form, MASH, can progress to scarring. In the phase 2 SYNERGY-NASH trial, tirzepatide resolved MASH without worsening fibrosis in around half to two-thirds of participants over a year, against about 10% on placebo. Semaglutide’s phase 3 ESSENCE trial reported similar resolution rates and, importantly, improvement in fibrosis. Neither medicine is yet licensed in the UK specifically for liver disease, but the direction of evidence is consistent.

Joints, mobility and inflammation

Carrying less weight reduces load on knees and hips, and both medicines have trial data on knee osteoarthritis: semaglutide’s STEP 9 trial reported a clinically meaningful reduction in knee pain scores over 68 weeks. Markers of low-grade inflammation such as CRP fall in most weight-management trials. These are real benefits, but they are largely benefits of weight loss rather than a separate action of the medicine, which is why they are also seen with bariatric surgery.

Kidneys

In people with type 2 diabetes and chronic kidney disease, the FLOW trial found semaglutide reduced the risk of kidney disease progression and related deaths by about 24%. Tirzepatide has shown slower decline in kidney function in analyses of its diabetes trials. Outside diabetes the evidence is thinner, and the practical kidney message for most people is the opposite one: vomiting, diarrhoea and not drinking enough on these medicines can harm the kidneys in the short term, which our kidneys and dehydration guide covers.

Mood, cravings and the claims to treat with care

Many people describe a quieter relationship with food, and some report less interest in alcohol. Early trials of semaglutide in alcohol use disorder have reported reduced drinking, and observational studies have linked GLP-1 use to lower rates of some other conditions, but none of this is established enough to be called a benefit of treatment. Mood effects cut both ways: weight loss often improves wellbeing, but the MHRA continues to monitor reports of low mood and, rarely, suicidal thoughts, and the leaflets advise telling your prescriber about any change in mood. Our page on emotional eating on Mounjaro looks at the psychological side in more depth.

Weighing benefits against risks

None of the above removes the side effects. Nausea, diarrhoea, constipation and tiredness are common, particularly early on; pancreatitis, gallstones and dehydration are uncommon but serious; and there is a small, still-debated signal for a rare optic nerve condition (NAION) with semaglutide that the MHRA updated its guidance on in February 2026. Benefits also stop when treatment stops: in the trials that withdrew medicine after a year, most of the weight and most of the improvements in blood pressure, lipids and HbA1c returned. Whether the trade-off is right for you depends on your starting risk, and that is a decision to make with a prescriber, not from a list of benefits. For a fact-check of the more alarming headlines, see sensational GLP-1 headlines versus the evidence.