The UK's most complete GLP-1 guide
Every Question Answered. Every Side Effect Explained.
- How GLP-1 medications work
- Mounjaro vs Wegovy compared
- Injection instructions
- Side effects & solutions
- What to eat on treatment
- FAQs answered
Free tracker included with every download this week
What Is the Minimum Weight for Mounjaro?
Mounjaro (tirzepatide) isn't prescribed based on a specific minimum weight — it's based on BMI and health conditions. In the UK, adults with a BMI of 30 or above, or a BMI of 27–29.9 with weight-related health conditions, may be eligible for this prescription-only injection. For South Asian, Chinese, Black African, or Black Caribbean adults, lower thresholds apply (BMI 27.5 or above). Use our free BMI calculator above to check whether your weight falls within the eligible range for your height.
10,000+ calculations today · NHS-aligned thresholds · 100% free
Calculate Your BMI Instantly
Enter your height and weight below. Supports both imperial (stone & lbs) and metric (kg). Results include NHS category, healthy weight range, and ethnicity adjustments.
What Is BMI and Why Does It Matter?
Body Mass Index (BMI) is the most widely used screening tool for assessing whether your weight falls within a healthy range. Used by the NHS, GPs, and weight management services across the UK, BMI provides a quick snapshot of your weight relative to your height. The formula is simple: your weight in kilograms divided by your height in metres squared (kg/m²).
While BMI isn't a perfect measure — it doesn't account for muscle mass, bone density, or fat distribution — it remains the standard first step in identifying potential weight-related health risks including type 2 diabetes, cardiovascular disease, high blood pressure, and certain cancers.
The NHS also recommends adjusted thresholds for people of South Asian, Chinese, or Black African heritage — a BMI of 23 or above is classified as overweight, and 27.5 as obese. Our calculator includes this adjustment as a one-click toggle.
UK Eligibility Criteria for Mounjaro
Mounjaro is a prescription-only, once-weekly weight loss injection licensed in the UK for adults meeting specific criteria. The minimum eligibility is determined by BMI, not absolute weight:
- BMI of 30 or above (obesity category)
- BMI of 27–29.9 with a weight-related health condition such as type 2 diabetes, prediabetes, high blood pressure, abnormal blood fats, sleep apnoea, or cardiovascular disease history
For people of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower thresholds due to increased health risk at lower BMI levels. A prescriber will assess your individual circumstances before issuing a UK prescription. This dual GIP and GLP-1 receptor agonist works alongside a reduced-calorie diet and physical activity — it is not a standalone solution.
Clinically BackedWeight Loss
No appointments. No waiting rooms. Just care — from a UK-regulated online pharmacy.
How It Works
Three simple steps to understand your weight and take action.
Enter your height and weight in our free calculator. Get your BMI, NHS category, healthy weight range, and ethnicity-adjusted thresholds instantly.
If your BMI suggests you're overweight or obese, explore our GLP-1 calculators to project potential weight loss on Mounjaro or Wegovy.
Use our progress tracker to log your weight weekly, visualise your journey with charts, and stay motivated — all stored privately in your browser.
Free Weight Loss Tools & Guides
Everything you need to understand your weight, explore medication options, and track your progress — completely free.
How Weight Translates to Mounjaro Eligibility
There is no single "minimum weight" for Mounjaro because weight alone doesn't determine eligibility — your BMI, height, and health conditions matter. For example, someone weighing 75kg may have a BMI of 27 if they are tall (eligible if they have a health condition), but the same 75kg in a shorter person could be a BMI of 32 (eligible regardless). Use our free weight converter and BMI calculator on this page to see where your weight sits on the health spectrum. If you're unsure, your GP can refer you to a specialist weight management service, or you can seek a private clinical assessment from a UK-licensed prescriber to determine your eligibility for this weekly weight loss injection.
- Dual GIP/GLP-1 receptor agonist
- Up to 22.5% body weight loss (SURMOUNT-1)
- Weekly injection, dose escalation over 20+ weeks
- Available via private prescription in the UK
- Doses: 2.5mg → 5mg → 7.5mg → 10mg → 12.5mg → 15mg
- GLP-1 receptor agonist
- Up to 15–17% body weight loss (STEP trials)
- Weekly injection, 5-step dose escalation
- NHS & private prescription available
- Doses: 0.25mg → 0.5mg → 1mg → 1.7mg → 2.4mg
Mounjaro vs Wegovy: Head-to-Head
A side-by-side comparison of the two most popular GLP-1 weight loss medications available in the UK.
| Feature | Mounjaro | Wegovy |
|---|---|---|
| Drug class | Dual GIP/GLP-1 agonist | GLP-1 agonist |
| Active ingredient | Tirzepatide | Semaglutide |
| Avg. weight loss | 15–22.5% | 12–17% |
| Key trial | SURMOUNT-1 (2022) | STEP 1 (2021) |
| Max dose | 15 mg weekly | 2.4 mg weekly |
| Escalation period | 20–32 weeks | 16–20 weeks |
| Administration | Weekly injection (pen) | Weekly injection (pen) |
| NHS availability | Private prescription only | NHS & private |
| Approx. private cost | £150–£250/month | £150–£300/month |
| Common side effects | Nausea, diarrhoea, constipation | Nausea, vomiting, diarrhoea |
Data sourced from SURMOUNT-1 and STEP 1 clinical trials. Costs are approximate and vary by provider. Always consult a prescriber.
Am I Eligible for Weight Loss Medication?
In the UK, eligibility for GLP-1 weight loss medications like Mounjaro and Wegovy is based on your BMI and overall health profile.
- BMI of 30 or above (obese)
- Age 18 or over
- No contraindicated conditions
- Committed to lifestyle changes
- BMI of 27 or above
- Plus type 2 diabetes
- Or high blood pressure
- Or obstructive sleep apnoea
Use our BMI calculator to check whether your BMI falls within the eligible range.
How We Built These Tools
Every calculator and guide on myweightcheck is built with accuracy and transparency in mind. Our BMI calculator uses the standard WHO formula with NHS-aligned category thresholds. Our GLP-1 projections are modelled on published clinical trial data from SURMOUNT and STEP studies.
All data stays on your device. We don't require sign-ups, and we don't store your health information on any server. Your progress tracker saves data locally in your browser using localStorage, so only you can see it.
We're based in the UK and our tools are designed specifically for UK users — supporting stone & lbs by default, referencing NHS guidelines, using NICE-approved medication data, and linking to GPhC-registered pharmacies.
Frequently Asked Questions
Common questions about BMI, weight loss medications, and our free UK tools.
Is there an absolute minimum weight to start Mounjaro?
No. Eligibility is based on BMI (27 or above with health conditions, or 30 or above regardless) and individual clinical assessment — not a specific weight in kilograms or stone. Your GP or prescriber will evaluate your overall health and circumstances.
What if I'm just under the BMI threshold?
If your BMI is just below 27, you would not typically qualify unless you have a diagnosed weight-related health condition such as type 2 diabetes or high blood pressure. Speak to your GP about your individual situation.
Do different ethnicities have different minimum weights for Mounjaro?
Not different weights, but different BMI thresholds. For South Asian, Chinese, Black African, or Black Caribbean adults, Mounjaro may be prescribed at a BMI of 27.5 or above due to higher health risk at lower BMI levels — reflecting NHS guidance on ethnicity-adjusted thresholds.
Can I get Mounjaro on the NHS if I meet the weight criteria?
Eligibility depends on your local NHS integrated care board. You can be referred by your GP to a tier 3 specialist weight management service. Waiting times and availability vary significantly across the UK. Private prescription is an alternative route if NHS access is limited in your area.
How does Mounjaro dosing start if I'm newly prescribed?
Mounjaro begins at 2.5mg weekly for 4 weeks, then increases to 5mg — this is standard dose titration. The prescriber adjusts the dose gradually (every 4 weeks minimum) up to the maximum 15mg based on tolerance and response. Individual results vary significantly.
Ready to take control of your weight loss journey?
Start with a free BMI check, explore your GLP-1 options, or begin tracking your progress today. No sign-up. No cost. Just results.