Emerging weight-loss injections, dubbed “super-jabs,” are poised to assist individuals who find it challenging to shed pounds with current medications like semaglutide and tirzepatide.
These innovative treatments are crafted to enhance and prolong the sensation of fullness, offering hope to those who may no longer respond to existing medications after just a few months of use.
Approximately 25% of patients experience either minimal weight reduction or hit a weight-loss plateau within six to 12 months of starting treatment with the drugs presently available.
Initial trials indicate that these new super-jabs could support patients in losing up to 25% of their body weight.
This potential outcome is a significant improvement over the typical 15% weight loss associated with semaglutide—marketed as Ozempic for diabetes and Wegovy for obesity—and tirzepatide, known as Mounjaro for diabetes and Zepbound for obesity.
“The initial batch of these medications targeted the hormone GLP-1 (glucagon-like peptide-1) to decelerate digestion and promote an earlier feeling of fullness,” explained Alex Miras, a clinical professor of medicine at Ulster University, in an interview with Good Health.
New treatments are designed to give a stronger and longer-lasting feeling of fullness
‘The second wave of new drugs combine GLP-1 with one or two extra hormones in order to make the treatments even more effective.’
Mounjaro was the first step in this direction. It works on two hormones, GLP-1 and GIP (glucose-dependent insulinotropic polypeptide), a gut hormone that triggers the release of insulin after a meal to mop up sugar (glucose) from the blood. When combined with GLP-1, GIP also makes the body feel fuller quicker, helping people eat less.
Another new drug – retatrutide – goes a step further by hitting three hormones at once: GLP-1 and GIP, plus glucagon, which nudges the body to burn stored calories, aiding weight loss.
Developed by Eli Lilly, the three-in-one jab has been shown to help people lose even more weight. A study in The New England Journal of Medicine in 2023 found most people shed more than 24 per cent of their body weight.
But now adding a different drug could produce the best results yet.
Amylin is a hormone that makes the body feel fuller quicker – and early results suggest that targeting it could help people lose up to 50 per cent more weight in the first month of treatment than with Wegovy or Zepbound alone.
Results for a new amylin drug called MET-233i, developed by US start-up Metsera, have been so impressive that it sparked a bidding war between two pharmaceutical giants Pfizer and Novo Nordisk. In October, Pfizer won – agreeing to buy the company for $10 billion (£7.6 billion).
Unlike weekly jabs with current weight-loss drugs, MET-233i only has to be injected once a month.
Amylin is a hormone released by the pancreas at the same time as insulin. As well as helping control appetite and blood sugar, it slows gastric-emptying and tells the brain you have had enough to eat.
An amylin-based drug called pramlintide has been used for years to control blood sugar in diabetes. Patients on it often lost weight, prompting researchers to investigate amylin’s potential for obesity.
Other amylin-based jabs are also in the pipeline.
Novo Nordisk has one called CagriSema, which combines amylin with semaglutide. Research shows it can help patients lose an average of 22.7 per cent of their body weight over 68 weeks – half those taking it lost a quarter of their weight.
Amycretin, another new amylin drug from Novo Nordisk, helped those on the highest dose lose 24 per cent of their body weight in just 36 weeks, according to a report in The Lancet earlier this year.
This is significantly more than the 15 per cent weight loss typically seen with the first-generation of drugs such as semaglutide.
‘About 20 per cent of people who use weight-loss jabs need to lose more than the current drugs [such as Wegovy and Zepbound] deliver,’ says Professor Miras.
‘These new combination jabs made with amylin seem to help people lose up to a quarter of their excess body weight.
‘This improves not only their weight but also obesity-associated complications, such as heart problems and high blood pressure.’
Meanwhile, Eli Lilly is also developing eloralintide – an amylin-only-based drug for those who cannot tolerate existing fat jabs due to side-effects, which can include nausea, vomiting, diarrhoea and constipation.
A study in The Lancet earlier this year found people on the drug lost up to 20 per cent of their body weight over 48 weeks and reported fewer side-effects.
But amylin could have another card up its sleeve.
Early findings from animal studies suggest it may also reduce the amount of muscle lost when taking weight-loss jabs. With current jabs, about a third of the weight lost is muscle while the rest is fat.
But doctors warn it’s not yet clear whether the same will happen in humans – and even if it does, the effects are likely to be small.
‘Muscle loss is normally around a quarter to a third of the total weight lost – no matter how someone is losing weight, whether through dieting or taking medication,’ says Professor Miras.
Dr Dimitris Papamargaritis, an associate professor in diabetes and endocrinology at the University of Leicester, adds that while amylin may slightly change how much energy the body burns during weight loss, it does not completely stop muscle being lost.
Novo Nordisk says it hopes to submit CagriSema for approval next year, meaning it could reach NHS patients as early as 2026.
Eli Lilly’s triple-hormone jab, retatrutide, will take another two to three years before it will be available on the NHS, as larger trials are only now under way, while its amylin-only drug, eloralintide, could take another five years.
Metsera’s once-monthly amylin jab is still in the early stages of testing, meaning it is unlikely to reach NHS patients until the early 2030s.
