MILLIONS of Brits "will have to wait" to take a lifesaving fat loss jab dubbed the "King Kong of weight loss drugs".
Fewer than 10 per cent of patients in England who are eligible for the drug will initially be able to access it on the NHS - after officials revealed they'll be dishing them out to be people with the highest needs first.
The "difficult decision" was made "in order to protect other vital NHS services", the National Institute for Health and Care Excellence (Nice) said.
The NHS spending watchdog has recommended Mounjaro - also known as tirzepatide and made by Eli Lilly - for those with a body mass index (BMI) of more than 35 and at least one weight-related illness.
This is estimated to account for about 3.4 million people.
To help the NHS manage demand, Nice said about 220,000 people in most need could be given the drug in an initial three-year period.
Read more on weight loss drugs
After this, the situation will be reviewed by Nice, who will provide further guidance on the rollout - which could take up to 12 years.
Mounjaro is a glucagon-like peptide-1 (GLP-1) agonist, a family of medications that help manage blood sugar.
It was initially given the green light to help manage obesity on the NHS in June, as part of draft guidance from Nice.
It said the once-weekly jab should be prescribed along alongside a reduced-calorie diet and exercise to help people lose weight.
Most read in Health
Other GLP-1 agonists include semaglutide - sold under the brand names Wegovy, Ozempic and Rybelsus.
Professor Jonathan Benger, chief medical officer at Nice, said: "The world will look very different in three years which is why we've taken the unprecedented decision to review the way this medicine is delivered to patients then.
"Tirzepatide and other drugs like it, such as semaglutide, will help people living with obesity to lose weight, and as a result will reduce their risk of developing heart disease or having a stroke.
"But tirzepatide is not for everybody, and only those with the highest clinical need will be treated initially.
"This means many people will have to wait.
"We have had to make this difficult decision in order to protect other vital NHS services and also to test ways of delivering this new generation of weight loss medications."
Final draft guidance published by Nice shows NHS England requested that Mounjaro is rolled out over a period of 12 years.
The watchdog recommends prioritising patients receiving care from specialist weight management services who will be able to access the drug within 90 days of the guidance being published on December 23.
Everything you need to know about fat jabs
Weight loss jabs are a hot media topic at the moment, with hundreds of success stories from people who shed the pounds.
In March 2023, the NHS announced it would make Wegovy, a drug made by Danish firm Novo Nordisk, available on prescription to thousands of obese Brits.
It contains the drug semaglutide, which is said to have helped reality star Kim Kardashian and Twitter boss Elon Musk lose weight.
Wegovy, which helped a third of people reduce their weight by 20 per cent in trials, is now available from pharmacies like Boots.
How do they work?
The jabs work by suppressing your appetite, making you eat less and therefore lose weight.
To do this, semaglutide mimics the role of a natural hormone, called GLP-1.
GLP-1 is part of the signalling pathway that tells your body you have eaten, and prepares it to use the energy that comes from your food.
London GP and founder of , Dr Zoe Watson, said: “Your body naturally produces an appetite regulating hormone called glucagon-like peptide-1.
“These jabs work by regulating your appetite, which can lead to eating fewer calories and losing weight.”
Aren’t they diabetes drugs?
Semaglutide, the active drug in Wegovy, was originally sold under the name Ozempic specifically for diabetes patients.
But people started noticing it helped suppress their appetites, stopping them eating as much and helping them shed the pounds.
Novo Nordisk then developed Wegovy, which contains the same chemical but at higher doses specifically to aid weight loss.
Wegovy is not prescribed for diabetes patients.
Can I get them?
Wegovy is offered on prescription to obese adults given specialist weight loss treatment.
The NHS currently also offers a similar drug called Saxenda, or liraglutide.
Both are only available throught specialist weight management services, which means you have to be referred to clinics led by experts.
GPs can’t prescribe them on their own, Dr Watson said.
The jabs have to be taken as part of an overall programme to help with lifestyle changes and psychological support to get the best effect from the medication prescribed.
Are there any risks?
Like all medicines, the jabs do not come without side effects.
Around half of people taking the drug experience gut issues, including sickness, bloating, acid reflux, constipation and diarrhoea.
Dr Sarah Jarvis, GP and clinical consultant at patient.info, said: “One of the more uncommon side effects is severe acute pancreatitis, which is extremely painful and happens to one in 500 people.”
Other uncommon side effects include altered taste, kidney problems, allergic reactions, gallbladder problems and hypoglycemia.
What other options are there?
Mounjaro (brand name for tirzepatide) also came onto the market in early 2024.
Like Wegovy, tirzepatide stems from a drug originally designed to treat diabetes.
The weekly injection helped overweight people drop more than two stone in 18 months.
It is available with to order with a prescription online from pharmacies including Superdrug and LloydsPharmacy Online Doctor.
It works in a similar way to Wegovy and Saxenda, but is more effective.
Dr Mitra Dutt from says: “Based on clinical trials, 96 per cent of people were able to lose more than five per cent of their body fat using Mounjaro. In similar trials, 84 per cent of people lost more than five per cent of their body weight on Wegovy, and 60 per cent on Saxenda.
“Mounjaro works by activating two hormonal receptors (GIP and GLP-1), which enhance insulin production, improve insulin sensitivity, and work to decrease food intake."
NHS England will develop a plan outlining other groups of patients that will be offered Mounjaro in the next three years, according to Nice.
Prof Benger added: "We want to help NHS England carefully manage the roll out of tirzepatide to ensure that other services are not impacted in a disproportionate way.
"Whilst the funding variation sets a maximum of 12 years, Nice will review the situation again within three years and provide further advice on how the roll-out of this medicine can be managed using the learning gained from the initial phase.
"This will ensure the roll out of tirzepatide reaches everyone who is eligible in a safe and effective way."
'Not a magic bullet'
The latest Health Survey for England shows 64 per cent of adults were overweight or obese in 2022.
However, Dr Kath McCullough, NHS England's national speciality adviser for obesity, warned that weight loss jabs "are not a magic bullet".
She said: "Obesity is one of the greatest public health issues facing the NHS and weight loss drugs, such as tirzepatide, are an important tool in helping people lose weight while also reducing the risk of other serious long-term conditions such as diabetes, strokes and heart attacks.
"However, on their own, weight loss drugs are not a magic bullet.
"They need to be prescribed by a healthcare professional alongside programmes that help people lose weight and live healthier lives by making changes to their diet and physical activity - and it's also crucial that they are prioritised for those who need them most.
READ MORE SUN STORIES
"This guidance enables the NHS to implement a phased roll out of tirzepatide to patients with the highest clinical need in a safe and effective way, while also protecting access to the NHS services that all patients rely on."
It comes as a trial by Mounjaro manufacturer Eli Lilly - known as Surmount-5 - found patients on tirzepatide recorded a weight loss of 20.2 per cent compared to 13.7 per cent in patients on semaglutide.