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
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What Does Mounjaro Do — How to Access It in the UK
Mounjaro (tirzepatide) is a prescription-only weight management injection that works by activating two natural hormone pathways — GIP and GLP-1 — to help reduce appetite and support weight loss alongside diet and exercise. If you're considering Mounjaro in the UK, understanding how to access it and what it costs is essential. This guide covers both NHS and private routes, helping you understand your options and what to expect from the consultation process.
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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.
How Mounjaro Works and What It Does
Mounjaro is a dual GIP and GLP-1 receptor agonist — this dual mechanism sets it apart from other weight loss injections like Wegovy. It works by activating two natural hormone pathways in your body: GIP (glucose-dependent insulinotropic polypeptide) and GLP-1 (glucagon-like peptide-1). These hormones are involved in appetite regulation and blood sugar control.
When you take Mounjaro, it may help you feel fuller after smaller meals, reduce cravings, and slow gastric emptying (how quickly food leaves your stomach). In clinical trials, participants on Mounjaro lost an average of 15–21% of their body weight over 72 weeks, though individual results vary significantly. You can estimate your potential weight loss using our GLP-1 weight loss calculator. The dose you receive is gradually increased over several weeks in a process called dose titration — starting at 2.5 mg and potentially reaching a maximum of 15 mg once weekly.
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.
Accessing Mounjaro in the UK — NHS vs Private
NHS access is limited and regional. NICE has approved tirzepatide for NHS specialist weight management services, but you must be referred to a tier 3 or tier 4 specialist centre by your GP. Waiting lists can be very long — many areas have backlogs of several months to over a year. Not all regions offer equal access.
Private access is available through GPhC-registered online pharmacies. You complete an online clinical assessment with a UK-licensed prescriber, who reviews your medical history, current medications, BMI, and eligibility. If approved, a prescription is issued and the medication is dispensed. Private consultations typically cost £40–£80, and medication costs range from approximately £129–£320 per month depending on dose. The process usually takes 24–48 hours from assessment to delivery.
Before pursuing any weight loss treatment, use our free BMI calculator to check where you currently sit on the NHS BMI scale. You'll need a BMI of 30 or above (or 27+ with weight-related health conditions) to be eligible. During an online consultation, you'll be asked about your weight history, diet, physical activity, any comorbidities (like high blood pressure or diabetes), and current medications — especially oral contraceptives, as Mounjaro may affect their absorption. Have your height and current weight ready, and be honest about your health conditions and previous weight loss attempts. The prescriber will assess whether Mounjaro is appropriate for you based on this information.
- 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.
What does Mounjaro actually do in your body?
Mounjaro activates GIP and GLP-1 hormone pathways, which help regulate appetite, increase feelings of fullness, and slow stomach emptying. This dual mechanism may help you eat less and feel satisfied with smaller portions, supporting weight loss when combined with a reduced-calorie diet and increased activity.
Can I get Mounjaro on the NHS in the UK?
Yes, NICE has approved tirzepatide for NHS specialist weight management services, but access is limited and varies by region. You'll need a GP referral to a tier 3 or tier 4 specialist centre. Waiting lists can be lengthy — many areas have delays of months to over a year.
How much does Mounjaro cost privately in the UK?
Private prescription costs vary by provider and dose. Online consultations typically cost £40–£80, and medication ranges from approximately £129–£320 per month depending on whether you're on a starting dose (2.5–5 mg) or a higher maintenance dose (10–15 mg).
What's the difference between Mounjaro and Wegovy?
Mounjaro is a dual GIP and GLP-1 agonist, while Wegovy is a GLP-1 agonist only. Mounjaro has a larger maximum dose (15 mg vs 2.4 mg) and clinical trials showed slightly higher average weight loss — but both are prescription-only, and individual results vary significantly.
How long does it take to be prescribed Mounjaro privately?
The private online consultation process typically takes 24–48 hours from initial assessment to prescription and delivery. NHS routes through specialist services are significantly longer due to waiting lists, which vary by region and can extend several months.
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.