Pharmaceutical company warns of risks from weight-loss drugs

George Yancopoulos, co-founder and chief scientific officer of Regeneron, has raised concerns about the long-term impact of popular weight-loss drugs, warning they could cause "more harm than good" due to rapid muscle loss.

Speaking as Regeneron pushes forward with trials of muscle-preserving treatments, Yancopoulos emphasised the need to address this issue to avoid potential health risks for patients using the drugs.

These medications, known as GLP-1s, are widely prescribed for weight loss, but clinical studies have shown that patients taking them lose muscle mass at a significantly faster rate than those shedding weight through diet and exercise. Yancopoulos warned that for the 40 per cent of patients who discontinue these treatments within a year, this rapid muscle loss combined with a rebound in body fat could lead to worse overall health.

“I do think that the GLPs should be viewed with a lot of concern in terms of the way they’re actually being used in the real world,” Yancopoulos said. He added that changes in body composition, with increased fat and decreased muscle, could potentially worsen health outcomes over time.

Regeneron is part of a growing group of companies researching ways to preserve lean muscle mass while patients use GLP-1 drugs. The company is testing a drug called trevogrumab, which blocks the hormone myostatin, known to limit muscle growth. This drug is being studied in combination with Wegovy in mid-stage clinical trials. There are currently 11 myostatin-blocking drugs in development, with seven being investigated for obesity treatment.

The rise of muscle-preserving therapies comes as companies like Novo Nordisk and Eli Lilly dominate the weight-loss drug market with treatments such as Ozempic, Wegovy, Mounjaro, and Zepbound. Eli Lilly has also moved to strengthen its position by acquiring biotech company Versanis for $1.9 billion, securing access to muscle-preserving treatments.

Clinical data has revealed that up to 40 per cent of the weight loss associated with GLP-1 drugs is due to lean body mass reduction, including muscle. Both the U.S. Food and Drug Administration and experts recommend that these medications be used alongside diet and exercise to mitigate this effect. Novo Nordisk, however, stated that its data did not show a disproportionate loss of lean body mass with semaglutide, the active ingredient in Wegovy.

Yancopoulos stressed that while GLP-1s may not be the ultimate solution to obesity and metabolic diseases, advancements in muscle-preserving treatments could lead to a healthier way of addressing these conditions.