A MAJOR review has pitted three blockbuster fat jabs against each other – comparing weight lost and how long users were able to maintain it.
Scientists compared tirzepatide – the active ingredient of Mounjaro – to semaglutide, which is in Wegovy and Ozempic, and liraglutide, that’s in Saxenda.
The reviews – published in the gold-standard Cochrane Database of Systematic Reviews – found tirzepatide helps users shed the most weight and keep it off longer than other GLP-1 drugs.
The weight loss dieters achieve on Mounjaro tends to last up to 3.5 years, researchers found.
All three jabs triggered significant weight loss compared to dummy drugs.
But data on how the drugs affect health in the long-term is lacking, the review authors noted.
Read more on weight loss jabs
GLP-1s – which stands for GLP-1 receptor agonists – work by mimicking a fullness hormone in the gut which tells the brain to stop hunger signals, reducing how much patients eat.
They were originally developed to treat diabetes – think Ozempic – but are now being prescribed for weight loss.
The Cochrane reviews were commissioned by the World Health Organization (WHO) to inform upcoming guidelines on the use of jabs to treat obesity.
They found Mounjaro users lost 16 per cent of their body weight in 12 to 18 months and were able to stay slim for the longest.
Those on Wegovy reduced their weight by 11 per cent in three to 16 months and maintained it for up to two years, but had higher rates of nausea, vomiting and constipation.
Saxenda users lost a more modest 5 per cent, though they were still more likely to achieve meaningful weight loss compared to people on placebo drugs.
“This effect is likely sustained at longer at longer-term follow-up,” researchers said.
But they noted that evidence for longer-term effects beyond two years was more limited.
The review found little to no difference between the drugs or placebo when it came to cardiovascular complications, quality of life, or mortality.
Side effects, nausea and digestive symptoms, were more common among GLP-1 users, and some stopped treatment due to side effects.
Juan Franco, co-lead researcher from Heinrich Heine University Düsseldorf, said: “These drugs have the potential to bring about substantial weight loss, particularly in the first year.
“It’s an exciting moment after decades of unsuccessful attempts to find effective treatments for people living with obesity.”
Eva Madrid, from the Universidad de Valparaíso, added: “We need more data on the long-term effects related to cardiovascular health.
“Weight regain after stopping treatment may affect the long-term sustainability of the observed benefits.
“More independent studies from a public health perspective are needed.”
Scientists flagged that many weight loss jab studies are funded and planned by drug manufacturers, raising the risk of biased results.
They also pointed out that high semaglutide and tirzepatide prices limit access to those in most need.
American drug giant Eli Lilly recently hiked drug prices for Mounjaro in the UK, with the highest dose costing upwards of £300 a month.
More than 1.5million people are estimated to be using the current injections, known as GLP-1 drugs, many buying them privately.
The jabs are only given on the NHS to people who are seriously overweight and already have health issues like diabetes or high blood pressure.
The Cochrane reviews will inform forthcoming WHO guidelines on the use of GLP-1 receptor agonists for treating obesity.
The guidelines are expected to launch soon, following a public consultation held in September.
