As this is a work related post first things first:

Disclaimer: This blog post adheres to the NMC Social Media Guidance. It reflects personal, evidence-based analysis and is not a substitute for individual clinical judgment.

Ok, that off the table now – shall we:

A quiet revolution has just landed in British GP surgeries — and no, it’s not another care pathway acronym. As of this week, GPs are officially allowed to prescribe weight-loss injectables, namely Wegovy (semaglutide) and Mounjaro (tirzepatide), under new NHS rules — provided patients meet strict eligibility criteria. These aren’t just fad drugs with celebrity endorsements.

They’re GLP-1 receptor agonists (and in Mounjaro’s case, a GIP/GLP-1 dual agonist) with serious metabolic credentials, and they’re shifting the ground beneath the NHS bariatric strategy. So, what exactly do they bring to the table — or rather, the syringe — and what does this mean for patients, practitioners, and the ever-buckling surgical waiting lists?

🔬 Mechanism of Action: Two Agonists, One Mission

Wegovy (semaglutide) mimics GLP-1, a hormone that promotes satiety, slows gastric emptying, and improves insulin regulation. Originally developed for type 2 diabetes as Ozempic, it soon found fame in weight management when trials revealed average losses of 15% body weight in non-diabetics (Wilding et al., 2021)

Mounjaro (tirzepatide) takes it a step further. It targets both GLP-1 and GIP receptors, offering dual action that leads to even greater weight loss — as much as 22.5% over 72 weeks, according to pivotal studies (Jastreboff et al., 2022). That’s not just impressive — it’s nipping at the heels of bariatric surgery in terms of total weight loss.

💉 Needles or Knives? Comparing Injectables and Surgery

Let’s address the elephant in the surgical suite: can these drugs replace bariatric surgery?

Dimension	Bariatric Surgery	Wegovy	Mounjaro
Avg. Total Weight Loss	25–35%	~15%	~22%
Duration	Permanent (variable)	Max. 2 years (NICE)	Max. 2 years (NICE)
Invasiveness	High	Low	Low
Long-Term Data	Yes (10–15 years)	Limited	None
NHS Cost	£5,000–£10,000 (one-off)	~£73/week	~£92/week (est.)
Side Effects	Surgical risks, nutritional deficiencies	GI effects, rare pancreatitis	Same, with more nausea reported

While neither injectable has the long-term durability of a gastric bypass, the non-invasive nature and metabolic benefits make them a compelling alternative for some, and a valuable adjunct to surgery for others.

⏳ What About the Bariatric Waiting List?

The UK’s bariatric surgery backlog is no small issue — in some areas, patients wait up to three years from referral to scalpel. Here’s where these injectables might make a dent.

Used as pre-operative tools, Mounjaro and Wegovy can reduce BMI, lower anaesthetic risk, and improve glycaemic control. Several weight management centres now prescribe them to optimise patients ahead of surgery — a kind of pharmacological “prehab.”

At the same time, injectables offer a non-surgical route for those who decline or don’t qualify for surgery. However, NICE guidance currently limits treatment duration to two years, and once stopped, weight regain is common (Rubino et al., 2021). That makes their use more of a bridge than a bypass in most cases.

🏥 How Are UK Bariatric Centres Using Injectables?

Real-world implementation is rapidly evolving. Several NHS specialist weight management services (Tier 3 and Tier 4) have adopted these injectables, but usage is highly variable depending on funding and staffing.

• Cheshire & Merseyside: Offers tirzepatide through community weight management with strict wraparound criteria.
• Surrey Heartlands ICS: Integrates both Wegovy and Mounjaro within MDT care.
• Imperial Weight Centre (London): Awaiting ICB pathway sign-off; not yet prescribing.
• Worcestershire Tier 3: Wegovy availability is limited by capped funding; no Mounjaro prescribing yet.

What’s clear is that injectables are not being offered in isolation. The best outcomes come from centres where pharmacological tools are embedded within a multidisciplinary model: dietitians, psychologists, physical activity, and ongoing monitoring.

⚠️ Side Effects and Cautionary Tales

Both Mounjaro and Wegovy are effective, but neither is risk-free. Without long-term safety data, especially outside of trial conditions, caution remains.

Common side effects:

• Nausea (up to 44%)
• Vomiting
• Diarrhoea or constipation
• Fatigue
• Headaches

More serious risks:

• Acute pancreatitis
• Gallstone disease (especially with rapid weight loss)
• Dehydration and kidney injury
• Reports of suicidal ideation (under MHRA review)

Of note, ‘Ozempic face’ — the facial volume loss seen in some rapid weight loss cases — is getting attention from aesthetic clinics, if not peer-reviewed journals (Kominiarek & Jungheim, 2023).

And importantly, stopping the medication often means weight comes back. The STEP-1 trial saw the majority of participants regain their weight within a year after discontinuing semaglutide (Rubino et al., 2021).

💷 Cost, Equity, and NHS Strategy

Injectables aren’t cheap. Weekly costs (~£73 for Wegovy, ~£92 for Mounjaro) add up, especially when considering the need for ongoing monitoring. While surgery is expensive upfront, it offers better long-term cost-per-QALY (NICE, 2023a).

Still, these drugs may reduce costs downstream — less diabetes, less cardiovascular disease, fewer surgical complications. The challenge lies in equitable access and ensuring GPs and Tier 3 centres are funded and trained to deliver wraparound support.

🧪 So… Are These Drugs the Future?

In short, yes — but not alone. Mounjaro and Wegovy bring undeniable benefit, particularly for patients who need urgent metabolic improvement or who can’t access surgery soon.

But without lifestyle support, psychological input, and a systems-based approach, injectables risk becoming yet another unsustainable intervention in the fight against obesity. Used wisely, however, they could buy time, reduce risk, and even ease the pressure on our creaking surgical systems.

References

Arterburn, D.E. and Courcoulas, A.P., 2014. Bariatric surgery for obesity and metabolic conditions in adults. BMJ, 349, p.g3961.

Davies, M.J. et al., 2021. Efficacy of liraglutide for weight loss in patients with type 2 diabetes. NEJM, 384(11), pp.989-1002.

Jastreboff, A.M. et al., 2022. Tirzepatide once weekly for the treatment of obesity. NEJM, 387(3), pp.205-216.

Kominiarek, M.A. and Jungheim, E.S., 2023. Aesthetic considerations in weight loss: beyond metabolic effects. Journal of Obesity Medicine, 7(2), pp.123-128.

MHRA, 2023. GLP-1 receptor agonists: risk of suicidal and self-harm thoughts. [online] GOV.UK. Available at: https://www.gov.uk/drug-safety-update

NICE, 2023a. Tirzepatide for managing overweight and obesity [TA1026]. Available at: https://www.nice.org.uk/guidance/ta1026

NICE, 2023b. Semaglutide for managing overweight and obesity [TA875]. Available at: https://www.nice.org.uk/guidance/ta875

Rubino, D. et al., 2021. Effect of continued weekly semaglutide vs placebo on weight loss maintenance. JAMA, 325(14), pp.1414-1425.

Wilding, J.P.H. et al., 2021. Once-weekly semaglutide in adults with overweight or obesity. NEJM, 384(11), pp.989-1002.