After fat-loss jabs you're likely to regain weight within 20 months, study finds
Research highlights need for ongoing support after treatment on jabs like Mounjaro, Wegovy and Ozempic
People using weight loss jabs put weight back on much faster than people who've lost weight with traditional dieting according to new research.
The University of Oxford's study showed people on drugs, including semaglutide (Wegovy) and tirzepatide (Mounjaro), regain their lost weight within an average of 20 months after stopping treatment.
Improvements to blood sugar levels, cholesterol and blood pressure are also lost when people stop the drugs, with patients ending up back where they were at the start of their diet journey.
In comparison, weight loss achieved through behavioral programmes focused on healthy diets and exercise lasted longer, with participants keeping the weight off for nearly four years on average, although on average, they eventually regained it.
The University of Oxford conducted a major study, involving more than 9,000 participants across 37 studies, which showed an average weight loss of 8.3kg during 10 months of treatment with weight loss drugs. However, 4.8kg was regained within the first year after discontinuation, with participants returning to their original weight within 1.7 years.
For people specifically on Wegovy and Mounjaro, weight loss totaled just under 15kg during treatment. However, within a year of stopping, 10kg was regained, and projections show that all weight is regained within 1.5 years.
Insights from leading researchers
Susan Jebb, professor of diet and population health at the University of Oxford, explained the findings:
“In summary, what we’ve shown in this particular piece of analysis is that weight regain after medication is common and is rapid," Jebb said. "The cardiometabolic benefits essentially parallel weight – and so as weight is regained, the cardiometabolic benefits are lost."
She highlighted that weight regain happens nearly four times faster with drugs compared to behavioral methods:
“It’s important to note that the rate of weight regain is almost four times faster than after behavioural programmes, and that’s regardless of the amount of weight loss during treatment.”
Jebb suggested that tackling obesity long-term might require lifetime solutions, such as sustained medication use, behavioral support, or a combination of both.
Addressing those considering intermittent treatments or tapering, Jebb admitted that there is no definitive answer:
“The jury is out on which strategy really works,” she said, adding that people paying privately for the drugs should be aware of the potential risk of rapid weight regain and the long-term financial implications.
Different research identifies ricks of weight loss jabs
Separate research from University College London and the University of Cambridge has identified risks associated with the new generation of weight loss drugs. These include potential nutritional deficiencies and muscle loss, as appetite suppression is not typically paired with structured guidance on diet quality or protein intake.
Dr Marie Spreckley of the University of Cambridge said:
“Many people receive little or no structured guidance on diet quality, protein intake, or micronutrient adequacy while experiencing marked appetite suppression.”
Without integrated nutritional care alongside treatment, Spreckley warned of the risk of replacing one health issue with another.
Further research outlined in the BMJ called for prolonged adherence or intermittent use of weight loss drugs if sustained health benefits are to be achieved.
NHS response
An NHS spokesman acknowledged the importance of pairing weight loss treatments with lifestyle changes:
“While these new treatments are an important new tool for supporting weight loss, they’re not a magic fix and must be paired with behavioural and lifestyle wraparound support including advice on healthier diets and physical activity to keep the weight off in the long term.”
“That’s why the NHS continues to implement innovative ways to support people to lose weight safely and sustainably as well as offering a range of weight management services, including the NHS Digital Weight Management Programme, which will be expanded to 125,000 more people per year as part of the 10-year health plan.”