What BMI you need for Mounjaro or Wegovy in the UK
The MHRA-licensed threshold for both Mounjaro and Wegovy is a BMI of 30 or above1,2.
At BMI 27 to 29.9, you can still access these medications privately if you have at least one weight-related health condition recognised by the product licence.
The recognised conditions are type 2 diabetes, prediabetes, high blood pressure, high cholesterol or dyslipidaemia (an unhealthy balance of fats in the blood), cardiovascular disease, and obstructive sleep apnoea1,2.
The NHS criteria are stricter. NICE TA1026 restricts NHS access to tirzepatide to adults with a BMI of 40 or above who have at least four of five qualifying conditions4.
The NICE ethnic BMI adjustment
NICE guideline NG246 (2025) sets a lower obesity threshold of BMI 27.5 for people from South Asian, Chinese, Other Asian, Middle Eastern, Black African, and African-Caribbean backgrounds3.
The adjustment is based on type 2 diabetes risk, not weight alone. Research in over 1.4 million people in England found that a BMI of 23.9 in South Asian populations carried the same type 2 diabetes risk as a BMI of 30 in White European populations5.
In practical terms, the obesity threshold drops from BMI 30 to 27.5, and the overweight-with-comorbidity threshold drops from 27 to 24.5.
The eligibility checker applies this automatically when you select your ethnic background.
Our guide to Mounjaro with prediabetes covers how the ethnic adjustment intersects with diabetes risk screening.
How the eligibility checker works
The checker uses three inputs: your BMI (from your height and weight), your ethnic background, and your weight-related health conditions.
It applies the standard MHRA thresholds, then applies the NICE NG246 ethnic adjustment (27.5, or 24.5 with a condition) for the relevant ethnic backgrounds.
It then checks the MHRA list for private eligibility, and the NICE TA1026 four-of-five list for the NHS, with the current rollout cohort applied automatically.
The verdict tells you which routes you fit into (NHS, private, off-label, or none) and the BMI threshold for each.
The three routes to weight-loss injections in the UK
| Route |
BMI threshold |
Conditions required |
Who decides |
| NHS (NICE TA1026) |
40+ (37.5+ ethnic-adjusted) |
4 of 5: T2D, hypertension, CVD, dyslipidaemia, OSA |
GP, where the local ICB participates |
| Private (MHRA-licensed) |
30+ (27.5+ ethnic-adjusted), or 27-29.9 with a comorbidity |
None at BMI 30+; at least one weight-related condition at 27-29.9 |
Private prescriber (e.g. Second Nature, Boots, Numan) |
| Off-label |
25-26.9 |
Not licensed; clinical justification varies by provider |
Some private providers (Second Nature doesn’t offer this) |
Route 1: NHS specialist weight management (NICE TA1026)
NICE TA1026 was published in December 2024, and the NHS England rollout for tirzepatide began on 23rd June 20254,6.
Year 1 (currently active) restricts access to adults aged 18 to 75 with a BMI of 40 or above, with at least four of five qualifying conditions4.
Year 2 (rolling out across 2026 and 2027) widens this to BMI 35 to 39.9 with the same four-of-five rule, and the threshold will continue to widen over the next 12 years6.
GP participation is voluntary, so coverage varies significantly by integrated care board (ICB, the regional NHS body that decides what’s funded locally).
Wegovy is also available on the NHS through Tier 3 specialist weight management services under NICE TA875, at BMI 35 with at least one comorbidity, capped at two years per course7.
Our guides to Mounjaro on the NHS and Wegovy on the NHS cover the referral pathways in detail.
Route 2: Private MHRA-licensed prescriptions
The MHRA licence allows private prescribing at BMI 30 or above, or BMI 27 to 29.9 if you have at least one weight-related comorbidity (a co-occurring health condition that justifies prescribing)1,2. This is the route most private GLP-1 patients in the UK take.
Mounjaro at its top dose (15 mg) produced an average weight loss of 22.5% in the SURMOUNT-1 trial8.
Wegovy at its top dose (7.2 mg) produced 20.7% in the STEP UP trial9.
The five qualifying conditions
The five qualifying conditions for the NHS pathway under NICE TA1026 are4:
- Type 2 diabetes
- High blood pressure (hypertension)
- Cardiovascular disease (previous heart attack, stroke, angina, or coronary procedure)
- High cholesterol or dyslipidaemia
- Obstructive sleep apnoea
For the private route, the Mounjaro and Wegovy product licences accept any one of these, plus prediabetes (an HbA1c blood-sugar reading between 42 and 47 mmol/mol)1,2.
PCOS and fatty liver disease aren’t on the licensed list, even though both are weight-related. Some private providers will prescribe the medications alongside these conditions, but this is off-label.
Our medication compatibility checker covers interactions among more than 40 specific conditions, medications, and weight-loss injections.
The off-label band (BMI 25 to 26.9)
Below BMI 27, weight-loss injections aren’t covered by the MHRA licence.
Some private providers (Voy is the most-cited UK example) will prescribe between BMI 25 and 26.9, but this is off-label, and Second Nature doesn’t.
The clinical trials that established how well Mounjaro and Wegovy work enrolled participants with a BMI of 27 and above with a comorbidity, or 30 and above8,9.
People with a BMI under 27 generally have a lower risk of weight-related health complications, but the side-effect risk from the medication stays the same.
At this BMI, you can achieve strong results without the risk of side effects associated with weight-loss injections.
Our non-medication programme includes registered dietitian support from £40 a month, around £309 cheaper than Mounjaro’s highest dose at £349 a month.
When BMI isn’t the right tool
BMI is a useful screening number, but it has known limits.
It doesn’t distinguish muscle from fat, and it doesn’t account for waist circumference, which is a better predictor of metabolic health in most people than BMI alone3.
Weight-loss injections aren’t recommended in these situations, regardless of BMI:
- If you’re under 18 (Mounjaro and Wegovy are licensed for adults)
- If you’re pregnant or breastfeeding
- If you’re currently struggling with, or recovering from, an eating disorder. Please don’t use the checker if this applies to you. Second Nature’s non-medication programme is a safer route, and many of our registered dietitians and coaches have specialist experience supporting disordered eating recovery
- If you have a personal or family history of medullary thyroid carcinoma or multiple endocrine neoplasia (these are FDA boxed warnings rather than UK contraindications, but they’re worth raising with a prescriber)
For adults aged 65 and above, the medication is still licensed and used, but a prescriber will pay particular attention to maintaining muscle mass, falls risk, and bone health.
What to ask any provider before starting
Once you’ve established you qualify, the right provider for you depends on titration (how the dose is increased), clinical oversight, and what happens when you come off:
- What’s your titration protocol? Some providers increase your dose by default every 4 weeks. Others (Second Nature included) work with you on a “lowest effective dose for as long as possible” approach.
- Who will I message when I have a question? Pharmacy-only providers route messages to whoever is on shift. Programme-based providers assign you a named coach.
- What clinical oversight is in place? Look for in-house doctors and clinicians who review applications and oversee ongoing care.
- What’s the plan for when I come off? The trials show that people who stop suddenly without support regain a significant proportion of the weight lost10. A clinical plan for coming off matters as much as the plan for starting.
Our guide to Mounjaro private prescriptions in the UK compares the major UK providers, and our switching Mounjaro providers guide covers what to expect if you move mid-course.
Second Nature has worked with the NHS since 2017, combining medication with structured habit-change support designed to help you avoid weight regain when you come off.
Take our 3-minute eligibility quiz, and a clinician will review your answers.
When your BMI drops below 27
Once you drop below the licensed threshold (BMI 27, or 24.5 if you’re using the ethnic-adjusted threshold), policies vary widely.
Some providers cut prescribing as soon as you drop below BMI 25. Others continue at a maintenance dose, on the reasoning that obesity is a chronic condition and stopping suddenly often leads to regain.
Emerging research shows that people who develop sustainable habits while on the medication are more likely to prevent weight regain in the long term11.
Maintenance dosing is a clinical decision made with the prescriber, not a fixed cut-off.
Our guide to coming off Mounjaro covers the options and includes a free weight regain prevention planner.
Frequently asked questions
Can I get Mounjaro with a BMI of 27?
Yes, if you have at least one weight-related health condition on the MHRA-licensed list (type 2 diabetes, prediabetes, high blood pressure, high cholesterol, cardiovascular disease, or obstructive sleep apnoea)1. Without one, BMI 27 is below the licensed threshold.
Do I need a qualifying condition if my BMI is over 30?
No. At BMI 30 or above (or 27.5 ethnic-adjusted), you can be prescribed Mounjaro or Wegovy privately without an additional condition1,2.
Does PCOS count as a qualifying condition?
PCOS isn’t on the MHRA-licensed list for Mounjaro or Wegovy, even though it’s a weight-related condition with strong evidence for GLP-1 benefit.
Some private providers will prescribe with PCOS at a BMI of 27 to 29.9, but this is off-label rather than within the licence.
Why are NHS and private criteria different?
The MHRA licenses what a medication can legally be prescribed for.
NICE decides which licensed uses the NHS will fund, which is usually a stricter subset due to funding and capacity constraints.
What is the ethnic BMI adjustment?
NICE NG246 (2025) recommends lower BMI thresholds (27.5 instead of 30, and 24.5 instead of 27) for South Asian, Chinese, Other Asian, Middle Eastern, Black African, and African-Caribbean backgrounds, because type 2 diabetes risk rises at lower BMIs in these populations3,5.
Will the prescriber tell my GP?
Most reputable private providers (Second Nature included) write to your GP, with your consent, to inform them you’ve started a weight-loss medication. This is good clinical practice and protects you if you need urgent care from an unfamiliar clinician.
Can I switch providers?
Yes. Most private providers accept new patients who’ve been prescribed elsewhere, subject to a fresh clinical review. Plan the move so you don’t run out of medication mid-titration.
Can I get weight-loss injections at BMI 25 or 26?
Not within the MHRA licence. Some providers prescribe off-label in this band, but Second Nature doesn’t, because the clinical evidence weakens significantly below BMI 27.
Take home message
There are three routes to a weight-loss injection in the UK.
The NHS pathway under NICE TA1026 currently restricts tirzepatide to a BMI of 40 or above with four of five qualifying conditions, with the threshold widening over the next 12 years.
The private MHRA-licensed route covers BMI 30 and above, or BMI 27 to 29.9 with at least one weight-related comorbidity.
Mounjaro at 15 mg produces an average weight loss of 22.5% in trials, and Wegovy at 7.2 mg produces 20.7%8,9.
Below BMI 27, prescribing is off-label, and Second Nature doesn’t prescribe medications to anyone with a BMI of below 27.
For South Asian, Chinese, Other Asian, Middle Eastern, Black African, and African-Caribbean backgrounds, NICE applies lower BMI thresholds based on equivalent type 2 diabetes risk, and the checker applies the adjustment automatically.
Once eligibility is established, look for a provider with a clear titration protocol, a named coach, in-house clinical oversight, and an explicit plan for coming off.
Second Nature has worked with the NHS since 2017, combining Mounjaro or Wegovy with structured habit-change support designed to help you avoid weight regain when you come off the medication.
In a 12-month study of 339 Second Nature members published in JMIR Formative Research, participants on tirzepatide lost an average of 22.1% of their body weight, and those on semaglutide lost 17.1%11.
Second Nature's Mounjaro and Wegovy programmes
Second Nature provides Mounjaro or Wegovy as part of our Mounjaro and Wegovy weight-loss programmes.
Why choose Second Nature over other medication providers, assuming you're eligible?
Because peace of mind matters.
We've had the privilege of working with the NHS for over eight years, helping people across the UK take meaningful steps toward a healthier, happier life.
Our programmes are designed to meet people where they are, whether that means support with weight loss through compassionate one-to-one health coaching, or access to the latest weight-loss medications (like Mounjaro and Wegovy) delivered alongside expert care from a multidisciplinary team of doctors, psychologists, dietitians, and personal trainers.
At the heart of everything we do is a simple belief: real, lasting change comes from building better habits, not relying on quick fixes. We're here to support that change every step of the way.
With over a decade of experience, thousands of lives changed, and a long-standing record of delivering programmes used by the NHS, we believe we're the UK's most trusted weight-loss programme.
We hope to offer you something invaluable: peace of mind, and the support you need to take that first step.
