Weight-loss medicine Mounjaro helps people shed significantly more weight than rival Wegovy, research suggests.
Key research pitching the drugs against each other found Mounjaro – nicknamed the “King Kong” of weight-loss medicine – was superior when it came to shedding pounds, though both drugs worked.
Experts presented their findings at the European Congress on Obesity in Malaga, Spain and published them in the New England Journal of Medicine.
Both Mounjaro (tirzepatide) and Wegovy (semaglutide) are weight-loss drugs that help people feel fuller for longer after eating and therefore less hungry. The research was sponsored by Eli Lilly and Company, manufacturer of Mounjaro.
The new randomised controlled trial involved 751 adults with obesity, but without Type 2 diabetes.
They received either Mounjaro at the maximum tolerated dose (10mg or 15mg) or Wegovy (1.7mg or 2.4mg) once a week for 72 weeks.
The typical age of those involved was 45 and most (65 per cent) were female, with a typical body mass index (BMI) of 39.
All had at least one known obesity-related complication, such as high blood pressure, sleep apnoea or heart disease.
The typical drop in body weight at the end of the trial was a 20.2 per cent reduction with Mounjaro and 13.7 per cent with Wegovy.
The drop in waist circumference was an average of 18.4cm with Mounjaro and 13cm with Wegovy.
People on Mounjaro were more likely to reach their weight loss goals, researchers found
One limitation to the study was that people knew which drug they were taking, though the researchers said the findings were in line with previous studies.
Dual action
Dr Louis Aronne, from Weill Cornell Medicine in New York, who led the research, said the dual action of Mounjaro may explain the findings.
Both Mounjaro and Wegovy mimic a hormone produced in the body called GLP-1 – a substance released in the gut when food is consumed.
This hormone slows the rate at which food is emptied from the stomach, reduces appetite via the brain and works on insulin levels.
But Mounjaro also mimics another hormone known as GIP (glucose-dependent insulinotropic polypeptide).
Dr Aronne said: “Our study shows that treatment with tirzepatide was superior to semaglutide with respect to reduction in body weight and waist circumference.
“Tirzepatide, while a single molecule, pharmacologically activates two metabolic receptors, GIP and GLP-1, which have both overlapping and non-overlapping expression and function.
“This dual agonism of tirzepatide may contribute to the higher weight reduction observed in the current study compared to semaglutide, a mono-agonist.”
As people lost weight in the study, health factors such as blood pressure and unhealthy blood fats all improved.
Speaking at the European Congress on Obesity in Malaga, Dr Aronne said: “This is actually the first head-to-head trial of two obesity medications, so I think we’re going to start seeing more of these as new medications become available.
“I saw a list the other day of 150 medications … that are now in development, so many people now realise how important it is to manage body weight in addition to other metabolic factors. I’ve called it the golden age of obesity treatment. It took a long time.”
Dr Aronne said semaglutide still remained an “extremely effective” weight loss medication and that the trial did not intend to minimise its effects.
He added: “If you have a patient with a BMI of 32, which is class-one obesity, they could get to a BMI in the mid 20s [with semaglutide], right around 25, which is normal.
“So the majority of people with obesity will do just fine on semaglutide. People at the higher end – class-two, class-three obesity – may ultimately do better with tirzepatide.”
Anti-cancer effect
Meanwhile, separate research presented at the conference suggests weight loss injections may have a powerful anti-cancer effect.
Experts already know losing weight reduces the risk of cancer, but now they believe weight-loss injections may have a role beyond simply helping people shed pounds.
This may be because weight loss drugs cut inflammation, researchers said, with newer medicine possibly having an even bigger effect.
However, one expert said more research is needed.
Weight loss drugs, also known as GLP-1 receptor agonists, work by reducing food craving.
These findings, published in the journal eClinicalMedicine, found first generation GLP-1 receptor agonists such as liraglutide and exenatide may have anti-cancer benefits beyond weight loss.
Researchers firstly discovered similar rates of obesity-related cancer among patients treated with the drugs and those given bariatric surgery.
Co-lead author, Dr Yael Wolff Sagy of Clalit Health Services in Tel Aviv, Israel, said they also found a “direct effect” of GLP-1 receptor agonists beyond weight loss “to be 41 per cent more effective at preventing obesity-related cancer”.
She added: “We do not yet fully understand how GLP-1s work, but this study adds to the growing evidence showing that weight loss alone cannot completely account for the metabolic, anti-cancer and many other benefits that these medications provide.”
