Am I Eligible? BMI and Weight-Loss Medication Explained
Weight-loss medication is everywhere right now — and one of the first questions we hear is a refreshingly simple one: am I actually eligible? The good news is that it comes down to a handful of clear things, and your BMI is the headline number. Here’s how it works, minus the jargon.
⏱️ The 30-second version
- Eligibility usually starts at a BMI of 30 or above — or 27 or above if you also have a weight-related health condition.
- Some ethnic backgrounds are assessed at slightly lower BMI thresholds.
- BMI is the starting point, not the whole story — your clinician looks at the bigger picture.
- It’s a prescription-only medicine for a reason: it isn’t right for everyone, and a clinician confirms it’s safe for you before anything is supplied.
First things first: what is BMI, really?
BMI (Body Mass Index) is a quick screening number that compares your weight to your height. It won’t tell you everything about your health, but across the population it’s a reliable first signal of whether your weight might be raising your risk of certain conditions. In the UK, the standard adult categories look like this:
- Underweight — below 18.5
- Healthy weight — 18.5 to 24.9
- Overweight — 25 to 29.9
- Obesity, class 1 — 30 to 34.9
- Obesity, class 2 — 35 to 39.9
- Obesity, class 3 — 40 and above
🧮 The maths: BMI = your weight in kilograms ÷ (your height in metres × your height in metres). Prefer not to do the sums? Our online assessment works it out for you in seconds.
So… am I eligible?
For weight-loss medication, eligibility generally begins in one of two places:
- A BMI of 30 or above, or
- A BMI of 27 or above and a weight-related health condition (more on what counts below).
That’s the framework — but it’s a starting line, not a guarantee. The exact threshold that applies to you, and whether medication is appropriate at all, is something a Trimu clinician confirms during your consultation, based on your full history. We’ve kept the specifics there on purpose: it’s a clinical decision, not a box-ticking exercise.
BMI doesn’t tell the whole story
BMI is a brilliant first filter, but it’s a blunt one. It can’t see the difference between muscle and fat, or where you carry weight. That’s why your clinician also considers things like your waist measurement, your medical history, and your day-to-day health — not just one number.
⚠️ Worth knowing: if you’re from a South Asian, Chinese, other Asian, Middle Eastern, Black African or African-Caribbean background, the health risks linked to weight can begin at a lower BMI. UK guidance reflects this with slightly lower thresholds for these groups. If that’s you, do mention it — it can change the picture, and your clinician will factor it in.
What counts as a “weight-related condition”?
If your BMI is between 27 and 30, having one of these alongside it is what typically opens the door. Common examples include:
- Type 2 diabetes (or prediabetes)
- High blood pressure
- High cholesterol
- Obstructive sleep apnoea
- Heart disease or other cardiovascular conditions
This isn’t an exhaustive list, and you don’t need a diagnosis already in hand — part of the assessment is exactly this conversation. If you’re not sure whether something counts, flag it anyway.
When medication isn’t the right fit
Meeting the BMI threshold is one half of the equation. The other half is making sure the medication is safe for you specifically. There are some situations where it isn’t suitable, or where extra care is needed.
🚫 Not suitable in pregnancy. These medicines must not be used if you’re pregnant, breastfeeding, or trying to conceive, because there isn’t enough safety data for an unborn baby. The MHRA advises using effective contraception while taking them — and some need to be stopped a couple of months before trying for a baby. If pregnancy is on your radar, tell your clinician so you can plan safely.
⚠️ Tell us about these — they may rule it out or change the plan:
- A history of pancreatitis (inflammation of the pancreas)
- Type 1 diabetes
- A personal or family history of certain thyroid cancers (medullary thyroid cancer / MEN 2)
- Severe digestive problems such as gastroparesis (slow stomach emptying)
- Other GLP-1 medicines you’re already taking, or a history of an eating disorder
Your safety: what’s normal, what to check, what’s urgent
If you do start treatment, here’s a simple traffic-light guide to side effects. Keep it handy — most people only ever deal with the green column.
🟢 Usually normal
Mild nausea, a smaller appetite, feeling full quickly, and the odd bit of tummy upset — especially in the first few weeks or just after a dose increase. These are common and tend to settle as your body adjusts. Eating smaller meals and staying hydrated helps.
🟠 Check in with your clinician
Side effects that aren’t settling, sickness or diarrhoea that’s leaving you dehydrated, ongoing vomiting, a planned pregnancy, or starting a new medication. Also get in touch before you make any changes yourself — message us through your patient portal and we’ll help.
🔴 Seek urgent medical help
Severe, persistent stomach pain — which may spread to your back and come with nausea or vomiting — can be a sign of acute pancreatitis. It’s rare, but it’s serious. Stop the medication and get urgent medical attention: call 111, or 999 if the pain is severe. The same goes for any signs of a serious allergic reaction, such as swelling of the face, lips or throat, or trouble breathing.
Find out where you stand — in minutes
Our free online assessment works out your BMI, checks the basics, and connects you with a Trimu clinician who’ll confirm whether weight-loss treatment is right for you. No awkward GP waiting room required.
✨ Meet “My Journey”
Eligibility is just the start. Inside your Trimu patient portal, My Journey is your personal home base for weight loss: track your weight and progress over time, see your milestones, get gentle nudges and check-in reminders, and message your clinical team whenever something comes up. It’s designed to keep you supported between appointments — not just at them.
Frequently asked questions
What BMI do I need to qualify?
As a rule of thumb, a BMI of 30 or above, or 27 or above with a weight-related health condition. Some ethnic backgrounds are assessed at slightly lower numbers. Your clinician confirms what applies to you.
Does my ethnicity really change the threshold?
Yes. For people from South Asian, Chinese, other Asian, Middle Eastern, Black African or African-Caribbean backgrounds, weight-related health risks can start at a lower BMI, so UK guidance applies lower thresholds. It’s worth mentioning in your assessment.
I’m a healthy weight but want to lose a few pounds — can I still get it?
No. If your BMI is in the healthy range, weight-loss medication isn’t appropriate, and a responsible clinician won’t prescribe it. It’s a treatment for managing weight-related health risk, not a cosmetic shortcut — and it isn’t risk-free.
My BMI is over 40 — does that mean I’m automatically approved?
A higher BMI doesn’t auto-approve you. Eligibility still depends on the full safety picture — your medical history, other medicines, and whether the treatment is suitable for you. The assessment is there to get this right.
Is BMI the only thing you look at?
No — it’s the starting point. Your clinician also considers your waist measurement, existing health conditions, current medications, and your goals before recommending anything.
How do I actually find out if I’m eligible?
The quickest way is our free online assessment. It takes a few minutes, calculates your BMI for you, and routes you to a Trimu clinician for a proper review.
Looking for something else?
We cover more than weight loss. Explore our other treatment pathways:
Medical disclaimer. This article is for general education and isn’t a substitute for personalised medical advice. Weight-loss medication is a prescription-only medicine and is supplied only after an online consultation with a Trimu clinician, who will confirm whether it’s appropriate and safe for you. Always read the patient information leaflet that comes with your medicine, and report any suspected side effects to your clinician or via the MHRA Yellow Card scheme (yellowcard.mhra.gov.uk). Trimu (AO Health Ltd) is registered with the Care Quality Commission (CQC). If you think you’re experiencing a medical emergency, call 999. Information last reviewed June 2026.
