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
Does Mounjaro Burn Fat or Just Suppress Appetite?
Mounjaro (tirzepatide) works through dual hormone pathways rather than simply suppressing appetite alone. It activates both GIP and GLP-1 receptors, which helps regulate how your body handles food intake, glucose control, and fat utilisation. In clinical trials, participants lost an average of 15–21% of body weight, though results vary significantly between individuals. Understanding how Mounjaro actually works — and what it costs in the UK — can help you decide if prescription weight loss treatment is right for you. Use our free GLP-1 weight loss calculator to explore potential outcomes at different doses.
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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.
How Mounjaro Actually Works: Beyond Simple Appetite Suppression
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist, which makes it different from single-action weight loss injections like Wegovy (semaglutide). Rather than simply reducing appetite, Mounjaro works on multiple biological systems:
- GIP activation helps regulate fat storage and glucose metabolism
- GLP-1 activation reduces hunger signals and slows gastric emptying
- Combined effect supports better blood sugar control and reduced cravings
Clinical evidence from the SURMOUNT trials showed that at the maximum 15mg dose, participants achieved average weight loss of approximately 20.9% of body weight over 72 weeks. The drug also improves how your body utilises energy, not just appetite suppression. However, weight loss plateaus if you discontinue treatment, and results depend heavily on lifestyle changes — reduced-calorie diet and increased physical activity are essential. Individual responses vary based on genetics, starting weight, and adherence to the medication regimen. Your prescriber will tailor your Mounjaro dose titration based on tolerance and response.
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.
Mounjaro Cost in the UK: NHS vs Private Access Routes
NHS access: Mounjaro is approved by NICE for use within specialist tier 3 weight management services, but access is limited and varies significantly by region. Waiting lists can be lengthy — often 6–12 months or longer in many areas. When available on the NHS, there is no direct cost to you, though you'll need GP referral and assessment by a specialist weight management team.
Private access: You can obtain a Mounjaro prescription privately through a GPhC-registered online pharmacy following an online clinical assessment with a UK-licensed prescriber. Private prescriptions typically cost between £129–£250 per month depending on dose. The KwikPen device (4 weeks' supply per pen) is dispensed by the pharmacy. Private access is faster and does not require NHS referral — you can start treatment within days of assessment. Your GP can still monitor your progress if you inform them of private 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.
Does Mounjaro burn fat directly or just reduce hunger?
Mounjaro uses dual GIP and GLP-1 pathways to support fat utilisation and glucose metabolism, not just appetite suppression. The GIP component specifically helps regulate how your body stores and uses fat. Combined with GLP-1's appetite-reducing effects, this dual mechanism is why Mounjaro may produce greater weight loss than single-action GLP-1 injections in some clinical studies. Individual results vary significantly.
How much does Mounjaro cost on the NHS in the UK?
Mounjaro is free on the NHS if prescribed through a specialist tier 3 weight management service, though availability and waiting times vary greatly by region. Some areas offer it readily; others have waiting lists of 12+ months. Your GP can refer you, but specialist assessment is required first.
Can I get Mounjaro privately without NHS referral in the UK?
Yes. Private prescriptions are available through GPhC-registered online pharmacies following an online clinical assessment with a UK-licensed prescriber. Private costs typically range from £129–£250 per month depending on dose. This route is faster than NHS specialist referral and doesn't require GP involvement, though it's advisable to inform your GP of private treatment.
What is Mounjaro dose titration and how does it affect cost?
Mounjaro dose titration is the gradual increase in dose over 16–20 weeks: starting at 2.5mg, increasing weekly through 5mg, 7.5mg, 10mg, 12.5mg, up to a maximum of 15mg. Each dose level requires a separate weekly injection. Higher doses cost more privately — the maximum 15mg dose is more expensive than maintenance doses of 5–10mg.
Is Mounjaro the same as Wegovy, and do they cost the same?
No. Mounjaro (tirzepatide) is a dual GIP+GLP-1 agonist, while Wegovy (semaglutide) is a GLP-1 agonist only. Mounjaro has shown slightly higher average weight loss in trials. UK private costs are similar (around £129–£250/month depending on dose), but maximum doses differ: Mounjaro goes to 15mg weekly, Wegovy to 2.4mg weekly. Both require prescription and clinical assessment.
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.