Short Takes: New obesity drug triumphs, online clinics shine
A new obesity drug outperforms the competition; online clinics deliver weight loss at lower doses, indicates research presented at the presented at the 2025 European Congress on Obesity.
New kid on the block
MALAGA, SPAIN — The first head-to-head study comparing obesity medications has shown that the dual action medication tirzepatide (Mounjaro, Zepbound) is more effective at achieving weight loss and reducing waist circumference than the blockbuster drug du jour semaglutide (Ozempic, Wegovy, Rybelsus).
Louis J. Aronne, MD, from the Comprehensive Weight Control Center at Weill Cornell Medicine in New York, NY, and colleagues conducted the SURMOUNT-5 trial to compare semaglutide, a long-acting GLP-1 receptor agonist, and tirzepatide, which targets both GLP-1 and a protein known as GIP, in just over 750 people with obesity but without type 2 diabetes.
The results, which were also published in the New England Journal of Medicine, showed that, after 6 years of treatment, the average reduction in weight with tirzepatide was 20.2% compared with 13.7% with semaglutide, which equated to an average weight reduction of 22.8 kg versus 15.0 kg.
In addition, more people treated with tirzepatide achieved reductions in body weight of at least 10%, 15%, 20% and 25% from the start of the trial. Interestingly, and in contrast to weight loss trials with other types of obesity medications, women lost approximately 6% more weight than men with either drug.
There was also an 18.4 cm reduction in waist circumference with tirzepatide compared with just 13.0 cm on average with semaglutide. Rates of unwanted, or adverse, effects with the drugs were comparable, with the majority mild to moderate in severity and mostly affecting the gut.
In a press conference, Aronne stressed that he did not want to downplay the effectiveness of semaglutide, as it is “extremely effective,” and pointed out that the majority of people with obesity weigh “a lot less” than the average body weight in the trial of 112.7 kg (approximately 17 stone, 10 pounds (lb), or 248 lb).
“So the majority of people with obesity will do just fine on semaglutide,” he said. “People at the higher end [of] obesity may ultimately do better with tirzepatide, but semaglutide has a lot going for it.”
More bang for your buck
Individuals attending an online obesity clinic that combines intensive lifestyle therapy with personalised semaglutide treatment achieved the same impressive weight loss results as seen in clinical trials, but at less than half the doses, reveals an analysis.
“Achieving the same weight loss in day-to-day life as in the tightly controlled conditions of a clinical trial, while also using lower doses of drugs, has many potential benefits, from lower costs and fewer side-effects for patients, to ensuring that stocks of the drug go further,” said lead researcher Henrik Gudbergsen, MD, PhD, MPA, lead researcher and Chief Medical Officer of Embla, ApS, an online weight loss service from Denmark.
It is well known that the results seen in clinical trials are difficult to replicate in the real world, as people often struggle to maintain the changes to diet and exercise that increase the likelihood of achieving the desired weight loss, and it appears that few follow the standard dosing schedules and instead stay on lower doses.
In the first study of its kind, which is due to be published in The Lancet Digital Health and goes by the acronym TRIM, Gudbergsen and colleagues examined the real-world effects of an online weight loss programme that provides intensive behavioural therapy and advice on diet and exercise, as well as doses of semaglutide that are tailored to individual patients.
The programme included advice on healthy eating, increasing exercise and on how to use cognitive behavioural therapy (CBT) and other therapies to overcome psychological barriers to weight loss. This was accompanied by access to doctors, nurses and psychologists through an AI-powered app, alongside a course on semaglutide.
Furthermore, participants were started on the lowest effective dose of the drug, and increases were only considered if they had stopped making progress, in an approach known as “treat to target.” If they maintained a weekly weight reduction more than 0.5% of their body weight and had manageable levels of side-effects and hunger, they remained on their current dose. Treatment continued until they reached their desired weight or a body mass index of 25 kg/m2.
The average weight loss for those who were still taking part in the programme was 12.2%, or 12.2 kg (1 st 13 lb or 27 lb), after six months, 16.2%, or 16.3 kg (2 st 8 lb or 36 lb) after one year, and 16.7%, or 16.8 kg (2 st 9 lb or 37 lb) after just over five years.
This is similar to the 15%–16% weight loss achieved by patients who took part in clinical trials in which semaglutide was combined with lifestyle interventions such as calorie-controlled diets and behavioural therapy, although the average dose in the current study was just 1 mg per week, less than half of that used in the trials.
“This approach was effective across all age groups and all starting weights and in both sexes,” said Gudbergsen.
The SURMOUNT-5 trial was funded by Eli Lilly. The TRIM trial was funded by Embla, ApS.
Aronne declares relationships with Altimmune, Amgen, AstraZeneca, Boehringer Ingelheim, Eli Lilly, ERX Pharmaceuticals, Intellihealth, Jamieson Wellness, Janssen Biotech, Jazz Pharmaceuticals, Novo Nordisk, Pfizer, Senda Biosciences, Skye Bioscience, Veru, Zealand Pharma. Gudbergsen is an employee of and has stock options in Embla, ApS.
Liam Andrew Davenport is a medical reporter with more than 20 years’ experience covering a wide range of specialties and topics in the field.