Weight management was transformed in 2023, with soaring use of the drug Wegovy, or semaglutide. Never before has there been an approved weight loss medicine that is so effective and yet also considered reasonably safe, writes Clare Wilson.

“The medical therapy of obesity has been revolutionised,” says Daniel Drucker at the University of Toronto, Canada.

Amid near constant media coverage, demand for Wegovy rose so much that supplies in some pharmacies ran out in the US, where the drug was launched in 2021.

This led to knock-on shortages of Ozempic, the version of semaglutide used to treat type 2 diabetes.

Semaglutide mimics the actions of a hormone called GLP-1, which is normally released after eating.

This has several effects on the body, including cutting appetite and triggering the release of the hormone insulin, which regulates blood sugar.

GLP-1 mimics were developed to treat type 2 diabetes, but their effects on appetite meant they were then approved as weight loss treatments for people without diabetes.

In fact, these medicines cause even more weight loss in people without diabetes, by as much as 15 per cent.

Following Wegovy’s US launch, the drug’s Danish manufacturer Novo Nordisk couldn’t keep up with demand and repeatedly delayed its other launches, but it has since been made available in some European countries, such as the UK.

Novo Nordisk’s obesity medicine sales rose by about 160 per cent between January and June this year, primarily driven by Wegovy sales in the US.

The firm had to limit supplies of the lower starting dose of Wegovy in that country to help those who had reached the higher maintenance dose continue treatment without interruption, as when people stop taking the medicine, weight slowly but inexorably returns.

In many countries, people who want semaglutide for weight loss have resorted to taking Ozempic, as doctors may prescribe this “off label” even for people without diabetes.

The end result is that those seeking semaglutide may have to call round multiple pharmacies to find stock.

“It is stressful for people to have to spend so much time and effort to get the medicine they need,” says Drucker.

Some nations, such as the UK, have brought in export bans for semaglutide-based drugs. The state of British Columbia in Canada has introduced stricter rules about people needing to have a diabetes diagnosis before they can get Ozempic.

One option for increasing supply is to switch people to other GLP-1 mimics that work in a similar way, such as liraglutide (Saxenda), but these are somewhat less potent for weight loss, so are being used at higher doses, says Drucker.

People are even resorting to buying the GLP-1 mimics from illegal sources online, with dangerous results.

The UK’s Medicines and Healthcare Products Regulatory Agency warned in October that some people had ended up in a coma after using counterfeit versions of Ozempic injection pens.

The fakes seem to have been insulin injection pens given new labels, as some of the users had gone into a coma due to plunging blood sugar levels. All of this demonstrates the incredible desire for solutions to obesity.

Mike Lean at the University of Glasgow, UK, says the demand for a new drug outstripping supply so much has happened only a few times previously, such as when anti-HIV drugs came out in the 1990s. 

“This has almost never happened before,” he says.