The mass rollout of weight loss jabs on the NHS in England started on Monday, with GPs now allowed to prescribe the drugs for the first time. Around 220,000 people with “greatest need” are expected to receive Mounjaro, also known as tirzepatide and described as the "King Kong" of weight loss jabs, through the NHS over the next three years.

Initially developed to treat Type 2 diabetes, Mounjaro lowers blood sugar levels and slows down how quickly food is digested. GPs in England can prescribe Mounjaro to severely obese people who also suffer from a range of other health problems. Patients previously needed to access the drugs through a special weight loss service.

But leading family doctors said some GPs have expressed concern about the additional workload linked to the rollout. And pharmacy experts also said there could be pressure on supplies of the drug, made by Lilly.

In the first year of the programme, the drug will be offered to people with a body mass index (BMI) score of over 40 who have at least four other health problems linked to obesity, such as type 2 diabetes, high blood pressure, heart disease, and obstructive sleep apnoea.

Estimates suggest around 1.5 million people in the UK are already taking weight loss drugs, which may have been prescribed through specialist weight loss services or via private prescription.

Professor Kamila Hawthorne, chairwoman of the Royal College of GPs, said: “While we recognise the potential benefits of weight loss drugs, we know many GPs are concerned about the implications of the rollout of weight loss drugs into general practice, both in terms of workload and training to appropriately initiate and manage these treatments.

“The college shares these concerns, which is why we were pleased NHS England suggested a phased roll-out of Mounjaro as a treatment for weight loss. As and when this is escalated, appropriate resourcing for general practice — including access to ‘wraparound’ services — and training for GPs must follow.

She added: “GPs and our teams are already working under intense workload and workforce pressures, and this must be factored into this rollout in order to guarantee it can be delivered safely.

“More widely, whilst weight loss medications have a lot of potential benefits for patients who are struggling to lose weight and who meet all the clinical criteria for a prescription, they mustn’t be seen as a ‘silver bullet’ to aid weight loss.

“We also need to see a focus on prevention, stopping people from becoming overweight in the first place, so they don’t require a medical intervention later.”

Dr Hawthorne said there is no “one size fits all approach” and that the rollout of the jabs should not “come at the expense of other weight loss service”.

She continued: “The roll-out of weight loss medications in the NHS will need to be consistently evaluated to ensure that there is evidence that these prescriptions are of long-term benefit to patients.”

Around 29% of the adult population in the UK is obese.

Olivier Picard, chairman of the National Pharmacy Association, said: “The demand for weight loss jabs continues to rise sharply, and more GPs have been directing patients back to pharmacies after initial inquiries, to access these treatments privately.

“As the NHS is now moving to implement National Institute for Health and Care Excellence (Nice) guidance, and tirzepatide becomes prescribable to more patients, we expect to see prescription volumes increase rapidly.

“However, NHS provision won’t meet demand straight away, so we fully expect that many people will continue seeking it privately from a pharmacy.

“Pharmacists are experts in medication and many of us have lots of experience delivering weight loss injections as part of a package of care including lifestyle advice.

“We are well placed to help roll out weight loss treatment on the NHS, with the right funding to support it. The biggest concern we have is that prescribing these medications alone misses the point.

“They should be part of a comprehensive weight management strategy — combining lifestyle coaching, exercise, and nutritional guidance. In reality, many GPs lack the bandwidth to deliver the level of support needed to ensure proper understanding and follow-up.

“As a result, we could end up in a situation where patients are prescribed the medication, lose weight, and then experience rebound weight gain once the course ends — simply because the foundational lifestyle changes weren’t addressed.”