How high does your BMI have to be for Mounjaro — and is that the whole picture?

The myth: you need a BMI of 35 or 40 to qualify

This is the question our prescribers hear most weeks, and it usually comes from the same misunderstanding. People see the NHS figures (BMI 35 with comorbidities, or BMI 40 for the earliest NHS access cohort) and assume those are the only numbers that matter anywhere. They are not. Those thresholds are specific to NHS commissioning policy under NICE's technology appraisal TA1026, which determines when the NHS will fund treatment. The licensed eligibility criteria, set by the MHRA and Eli Lilly in the Mounjaro SmPC, are different and considerably more inclusive.

The licensed lower limit is a BMI of 30 for adults without any additional conditions. If you have at least one weight-related health condition (prediabetes, high blood pressure, obstructive sleep apnoea, high cholesterol, or osteoarthritis, among others) the threshold drops to a BMI of 27. That is the threshold that applies in the private setting, where a prescriber can treat anyone who meets the licensed criteria and for whom treatment is clinically appropriate.

So the myth that you need a BMI of 35 or higher applies to NHS funding only. Private treatment through a regulated online pharmacy follows the licensed thresholds. If you want a clear comparison of how the two routes work, our overview of BMI criteria for Mounjaro sets them out side by side, and our detailed guide to what BMI you have to be for Mounjaro walks through the numbers in full.

Why ethnic background can change the numbers

The BMI scale was developed using data that does not represent all body types equally. UK clinical guidance acknowledges this by applying lower thresholds for people from South Asian, Chinese, Middle Eastern, Black African and African-Caribbean backgrounds, generally 2.5 kg/m² below the standard figures. In practical terms, that means a BMI of 27.5 rather than 30, or 24.5 rather than 27 when a weight-related condition is present. NHS England's guidance on weight management injections sets out these adjustments in full.

This is not a loophole or a rounding-down of the rules. It reflects the clinical reality that health risks associated with higher body weight tend to appear at lower BMI readings in these populations. A prescriber working in line with current UK guidance will factor your background into the assessment. If you have wondered whether your BMI is close to the threshold, this adjustment may be relevant to you, and it is worth raising during a consultation rather than assuming you do not qualify.

There is a practical note worth adding here. The NHS BMI calculator lets you check your own figure before you take any further step, and it accounts for ethnic background in its feedback. It takes about a minute.

BMI is the starting point, not the finish line

Meeting the BMI threshold means you may be eligible. It does not mean treatment is automatically right for you. A prescriber also looks at your current medications, because some medicines interact with tirzepatide or affect how the pill or injection is absorbed. They look at your medical history, particularly any personal or family history of medullary thyroid carcinoma or a condition called MEN2. Pancreatitis history, gallbladder problems, and certain gastrointestinal conditions all factor in too.

Pregnancy, breastfeeding, and trying to conceive are situations where Mounjaro is not recommended. The same applies to anyone under 18. On contraception specifically, women using the oral contraceptive pill during tirzepatide treatment are advised to add a non-oral method for the first four weeks of treatment and for four weeks after each dose increase, because gastric slowing may reduce pill absorption, a detail worth keeping in a note next to the pen in the fridge door so it is not overlooked.

If you want to understand how weight-related conditions affect the assessment, our guide covering what your BMI has to be to get Mounjaro goes further on that question. And if you are already exploring what treatment costs in the private setting, our Mounjaro price page explains what an all-inclusive private prescription covers.

How a private clinical assessment works at nume

At nume, the process is straightforward. You complete a free consultation online, no referral, no waiting list. A GPhC-registered Independent Prescriber reads through your answers the same day, not software doing keyword matching. If they have questions, they ask. Identity is confirmed via photo ID, and weight is verified on video. Only after that review does any approval or prescription follow.

This level of scrutiny exists because Mounjaro is a prescription-only medicine and clinical assessment is not optional, it is the law. The Mounjaro treatment page explains what is included in a private prescription through nume: consultation, clinical review, prescription, and free next-working-day tracked delivery, all in one transparent price. If you have more general questions before starting, our page on what your BMI needs to be for Mounjaro is a useful read alongside the FAQs, which cover the most common ones, and our team is reachable through the contact page seven days a week. When you are ready, speak to our prescribers to begin.