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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Mounjaro Before And After — Cost And Access In The UK
When people search for "Mounjaro before and after", they're usually looking for two things: what results to expect and how much it costs in the UK. Mounjaro (tirzepatide) is a prescription-only, once-weekly weight loss injection licensed in the UK. Clinical trials showed participants lost an average of 15–21% of their body weight — though individual results vary significantly. Access depends on whether you go through the NHS or choose private prescription through a UK prescriber. This guide explains both routes, realistic costs, and what the evidence actually shows.
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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.
What Does Mounjaro Cost In The UK?
Mounjaro cost varies depending on your access route. Private prescription costs typically range from £129 to £320 per month depending on your dose, with lower doses (2.5–5mg) at the cheaper end and higher maintenance doses (10–15mg) at the upper range. Each KwikPen contains four weekly injections, so monthly costs are roughly equivalent to the cost per pen multiplied by four weeks of treatment.
NHS access is free at the point of use if prescribed through a specialist tier 3 or tier 4 weight management service, but waiting lists vary significantly by region — some areas have waits of several months to over a year. Not all NHS integrated care boards (ICBs) currently offer tirzepatide funding, so availability depends on where you live.
- Private online prescriptions: £129–£320/month depending on dose
- NHS specialist services: free but with regional variation and waiting lists
- Starting dose (2.5mg) is usually the most affordable option
- Costs increase as you escalate to higher maintenance doses
When budgeting, remember that Mounjaro is typically used alongside a reduced-calorie diet and increased physical activity — these lifestyle changes are free and essential to results.
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 Routes
NHS route: Your GP refers you to a specialist weight management service (tier 3). You'll be assessed for eligibility, have baseline health checks, and receive ongoing support. Free treatment but significant waiting lists in many areas. Best if you qualify and can wait.
Private route: You complete an online consultation with a UK-licensed prescriber, who assesses your medical history and BMI. If approved, a prescription is issued and dispensed by a GPhC-registered pharmacy. Takes days to a week, not months. You pay for each prescription upfront. Use our GLP-1 weight loss calculator to estimate potential results at different doses before committing.
Both routes require a genuine clinical assessment — Mounjaro is not available without prescription in the UK. Your prescriber will check your BMI, health conditions, current medications, and contraindications before approving treatment.
- 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 do "before and after" results typically look like with Mounjaro?
Clinical trial data (SURMOUNT-1) showed average weight loss of 15–21% of body weight over 72 weeks depending on dose. For a 100kg person, that's roughly 15–21kg loss. Individual results vary significantly based on diet adherence, activity level, genetics, and starting weight. Results are not assured, and some people lose less.
How long does Mounjaro take to show results?
Most people notice appetite reduction within 2–4 weeks of starting. Measurable weight loss (1–2kg) typically appears within 4–8 weeks. Significant results accumulate over 12–16 weeks as you escalate doses. Track your progress using our free progress tracker to monitor changes weekly.
Is Mounjaro cost covered by the NHS in my area?
NHS coverage for tirzepatide (Mounjaro) varies by integrated care board (ICB). Some areas offer it through specialist weight management services; others don't yet. Contact your GP or check your local ICB website to confirm. Even if available, waiting lists can be several months.
Can I switch from Wegovy to Mounjaro on the NHS?
Possibly, but both medications are typically accessed through specialist tier 3 services, not standard GP prescriptions. If you're on one medication privately and want NHS access to another, you'd need a new NHS referral and assessment. Your GP can advise on local eligibility.
What happens to weight after stopping Mounjaro?
Clinical evidence suggests weight regain occurs gradually after stopping Mounjaro, though more slowly than after some other weight loss approaches. Long-term weight maintenance depends on sustained lifestyle changes (diet and activity). Some people use Mounjaro long-term; others use it short-term to reset habits then maintain through diet and exercise alone.
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.