Drugs designed to treat diabetes and repurposed as miracle diet aids have taken over TikTok.

The weight loss caused by these weekly injectables is rapid and previously unattainable, people boast, showing off newly svelte bodies.

But what are these drugs, how do they work – and what were they originally designed to do?

Mounjaro, Ozempic, Wegovy – what are they?

Let’s start with the most well-known of the trio: Ozempic.

Ozempic blew up last year – if media reports from the US are to be believed, every pound dropped in LA was probably thanks to the “miracle” injectable drug.

What started as the preserve of A-listers and the Hollywood elite – rumours swirled that Kim Kardashian used it to fit into Marilyn Monroe’s dress – quickly grew in popularity.

Its generic name is semaglutide. This is the same as Wegovy, which has been licensed as a weight loss drug in the UK and will be available later this spring.

Wegovy has a slightly higher dosage and is designed for weight loss, while Ozempic’s primary purpose was as a diabetes treatment (more on that later).

Mounjaro – also known by its generic name tirzepatide – is the newer kid on the block.

Like Ozempic and Wegovy, it suppresses the appetite and lengthens the amount of time food stays in the stomach, leading to weight loss – at least for as long as you carry on taking it.

Last year the US Food and Drink Administration (FDA) fast-tracked approval of the drug to treat obesity after a study showed it helped people lose more than 20% of their bodyweight.

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Controversial drug Ozempic has taken over the internet

From diabetes drug to diet pill

Ozempic and Mounjaro were both initially developed as treatments for type 2 diabetes.

The drugs, which come as weekly injections, lower blood sugar by increasing insulin production when your blood sugar is rising and helping prevent your liver making and releasing too much sugar.

So how do they cause weight loss?

Both semaglutide and tirzepatide work by mimicking the hormone, GLP-1 (glucagon-like peptide one), to manage hunger and slow down digestion.

Tirzepatide – Mounjaro – is a dual-acting drug and also mimics the hormone GIP (glucose-dependent insulinotropic polypeptide).

In terms of weight loss, in clinical trials people lost up to 20% of their body weight on tirzepatide and 15% on semaglutide.

They sound like miracle drugs for people wanting to lose weight – what’s the catch?

There are a few downsides. First off, the listed side effects: nausea, vomiting and diarrhoea, bad enough for about 5% of people in the semaglutide trial to stop taking it and 6-7% in the tirzepatide trial.

People in the semaglutide trial also experienced problems with gallstones.

The drugs also carry serious risks including kidney failure, pancreatitis and thyroid cancer.

Another downside has been dubbed “Ozempic face”. Facial aging is a side effect of sudden weight loss as people find the skin on their face sagging where once it was plump.

Read more:
Controversial diet drug takes over the internet despite health warnings
Wegovy weight loss jab to launch at UK pharmacies

The drugs also only work for as long as you carry on taking them, and people have reported gaining back all the weight they lost after stopping the drug – either out of choice or because of a supply shortage.

Shortages for diabetics

Perhaps a bigger conversation than side effects for individuals is around the impact on people who rely on these treatments, now they’ve exploded in popularity as a weight loss quick-fix.

While intended for diabetics, Ozempic and Mounjaro are prescribed “off-label” in the US to people wanting to shed weight.

The drugs faced widespread shortage last year, with reports of diabetics having to drive from pharmacy to pharmacy in search of stock because of the high demand.

Are they available in the UK?

Ozempic and Mounjaro are not licensed in the UK.

Wegovy is available in the UK for type 2 diabetes patients with a prescription and is set to launch at UK pharmacies in spring.

It has been licenced in the UK specifically for weight loss and will be available with a prescription for those who have a body mass index (BMI) of 30 or over – or a BMI of 27 or over with health conditions related to weight.