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 Weight Do You Have To Be For Mounjaro?
To access Mounjaro (tirzepatide) in the UK, you need a BMI of at least 30 kg/m² or a BMI of 27–29.9 with weight-related health conditions. However, eligibility varies depending on whether you're accessing the weekly weight loss injection through the NHS or privately. This guide explains the weight thresholds, how UK prescription weight loss works, and what to expect when seeking Mounjaro.
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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.
Mounjaro Weight Eligibility & Cost in the UK
To qualify for Mounjaro in the UK, you must meet specific BMI-based eligibility criteria. The primary threshold is a BMI of 30 or above (obesity category). However, if your BMI is between 27 and 29.9 (overweight), you may still qualify if you have at least one weight-related health condition, such as type 2 diabetes, prediabetes, high blood pressure, abnormal blood fats, sleep apnoea, or a history of cardiovascular disease.
For adults of South Asian, Chinese, Black African, or Black Caribbean backgrounds, the NHS recommends lower thresholds due to higher metabolic disease risk at lower BMI levels. These individuals may qualify at a BMI of 27.5 or above. Using our free BMI calculator, you can instantly check your personal BMI and see where you fall on the NHS scale.
A prescription weight loss injection like Mounjaro is not automatically available to everyone who meets the BMI threshold—a clinical assessment must confirm suitability. Age, medications, medical history, and whether you're pregnant or breastfeeding all factor into eligibility. Your GP or a licensed prescriber will evaluate you individually.
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.
NHS vs Private Access: Cost & How to Get Mounjaro
NHS route: Mounjaro may be available through specialist tier 3 weight management services following a GP referral. Availability varies significantly by region and NHS Integrated Care Board, and waiting times can be substantial. If approved, the NHS covers the cost entirely, but access is not assured everywhere.
Private route: You can access Mounjaro privately through a UK-licensed prescriber via an online clinical assessment, typically without waiting for NHS services. A single Mounjaro pen (four weekly injections) costs between £129 and £280 depending on dose and provider. The 2.5 mg starting dose is usually the least expensive; higher maintenance doses cost more. Many people track progress using our free progress tracker while on treatment. Private prescriptions require a new clinical assessment, so costs and availability should be confirmed directly with providers.
- 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.
Do I need to be a specific weight to get Mounjaro in the UK?
No specific weight is required—eligibility is based on BMI. You need a BMI of 30 or above, or 27–29.9 with weight-related health conditions. Use our free BMI calculator to check yours. South Asian, Black African, and Chinese adults qualify at lower BMI thresholds due to higher metabolic disease risk.
How much does Mounjaro cost privately in the UK?
A single Mounjaro KwikPen (four weekly doses) typically costs £129–£280 depending on the dose strength and provider. Starting doses are usually cheaper than maximum doses. Costs vary between providers, so compare before committing. NHS provision is free but availability depends on your region.
Can I get Mounjaro on the NHS in the UK?
Yes, but only through specialist tier 3 weight management services following a GP referral. Availability varies significantly by region and waiting times can be long (months to years in some areas). Not all areas have consistent access. Private prescription may be faster if you meet clinical criteria.
What happens during a private Mounjaro consultation in the UK?
You complete an online health questionnaire covering medical history, current medications, weight, height, and health conditions. A UK-licensed prescriber reviews your information and assesses suitability. If approved, a prescription is issued and dispensed by a GPhC-registered pharmacy. The entire process typically takes 24–48 hours.
Is Mounjaro the same as Wegovy for weight loss?
Both are prescription-only weekly weight loss injections licensed in the UK, but they're different medications. Mounjaro (tirzepatide) is a dual GIP and GLP-1 agonist; Wegovy (semaglutide) is a GLP-1 agonist only. Clinical trials suggest similar average weight loss outcomes, though individual results vary. A prescriber will advise which suits you.
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.