What BMI do you need for semaglutide?

The myth: a BMI of 30 is all you need

It is easy to come away from a quick search thinking that hitting a BMI of 30 is a green light for semaglutide. That is not quite right, and getting it wrong can lead to real disappointment, or, worse, to sourcing medicines from sellers who ask no clinical questions at all.

What the UK licence actually says is that Wegovy is indicated for adults with a BMI of 30 or above alongside a reduced-calorie diet and increased physical activity. If your BMI sits between 27 and 29.9, the medicine is still licensed for you, but only when at least one weight-related condition is also present. That might be prediabetes, diagnosed hypertension, obstructive sleep apnoea or raised cholesterol, among others. The number on its own is a starting point, not a finish line.

A prescriber reviewing your consultation will also consider your full medical history: other medicines you take, any history of pancreatitis or thyroid conditions, and whether you are pregnant, trying to conceive or breastfeeding, semaglutide is not recommended in any of those situations. The clinical picture is broader than the BMI calculator suggests. A fuller breakdown of the criteria for semaglutide covers each of those conditions in more detail.

How the semaglutide BMI thresholds work in practice

The 30 and 27 figures come directly from the Wegovy Summary of Product Characteristics authorised by the MHRA, and they are also the thresholds referenced in NICE's technology appraisal of semaglutide (TA875). It is worth knowing, though, that NICE's NHS recommendation applies a higher bar: BMI 35 or above, within a specialist weight management service, for a maximum of two years. That reflects NHS prioritisation, not the medicine's licensed range.

Private prescribing follows the licensed range (BMI 30 or 27 with a comorbidity) which is why many people who do not meet the NHS threshold can still access Wegovy through a regulated private pharmacy. If you are unsure where your BMI sits, the NHS BMI calculator is a reliable starting point before you book a consultation.

The ethnic-background adjustment also matters here. Standard BMI thresholds were developed from predominantly white European datasets and are known to underestimate adiposity-related risk in South Asian, Chinese, Middle Eastern, Black African and African-Caribbean populations. UK guidance accounts for this by applying thresholds approximately 2.5 kg/m² lower, so the standard 30 effectively becomes 27.5 for those groups, and the 27 threshold shifts accordingly. Semaglutide at a BMI closer to 25 explores this adjustment in more depth.

What happens if your BMI changes during treatment

A question our prescribers hear regularly is whether ongoing eligibility depends on maintaining a particular BMI. The honest answer is that treatment is reviewed at each repeat, not on the basis of hitting a target number but on overall clinical suitability and progress. NICE guidance suggests that if less than five percent of body weight has been lost after six months on the maintenance dose, continuing should be reviewed.

Weight does shift during treatment, that is the point. A person who started at a BMI of 34 and has lost fifteen percent of their body weight may now sit below 30, and if you want to understand the evidence behind those outcomes, our page on once-weekly semaglutide in adults with overweight or obesity sets out the clinical picture in detail. The prescriber considers whether the medicine is still clinically appropriate, whether the person has qualifying comorbidities, and what the individual's health goals are. It is a conversation, not a one-time calculation. More on who can take semaglutide covers how those ongoing reviews tend to work.

If you are thinking about cost alongside eligibility, our Wegovy pricing page explains what a legitimate private prescription includes, it is a useful companion to understanding whether private treatment makes sense for your situation.

BMI and semaglutide: the number that starts the conversation

Understanding your BMI in relation to semaglutide eligibility is genuinely useful, it tells you whether you are within the licensed range before you spend time on a consultation. But it is worth holding the number lightly. BMI is a population-level screening tool, not a precise measure of individual health. Two people with identical BMIs can have very different cardiovascular risk profiles, metabolic histories and treatment needs, and our dedicated page on semaglutide at a BMI of 26 is a good example of how those individual circumstances shape eligibility in practice.

That is precisely why the UK requires a prescriber to assess every request for a prescription-only medicine like Wegovy. There is no shortcut that responsibly bypasses that step. At nume (sorry, at nume) a GPhC-registered Independent Prescriber personally reviews every consultation the same day; no automated decision-making, no algorithm standing in for clinical judgement.

If you have questions specific to your own health situation, our FAQs page covers many of the queries that come up most often. And if you are ready to find out whether semaglutide is suitable for you, a free consultation with our prescribers is the right next step. Speak to our prescribers and get a same-day clinical review.