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 Weight Loss Timeline: UK Cost & Access
Understanding how Mounjaro works and when you might expect to see weight loss results is crucial when considering this prescription medication. Mounjaro (tirzepatide) is a weekly weight loss injection available in the UK through both NHS specialist services and private online prescription routes. Results typically emerge gradually over several months, with individual timelines varying significantly based on dose, lifestyle, and personal factors. This guide covers the realistic weight loss timeline, UK costs, and how to access Mounjaro whether through the NHS or privately.
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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.
Mounjaro Weight Loss Timeline & Expected Results
Week 1–4 (Starting dose 2.5 mg): Most people experience initial appetite suppression and reduced food cravings. Measurable weight loss may not be apparent yet, though some users report feeling fuller after smaller meals. Nausea is common during this adjustment phase.
Week 5–12 (Dose escalation to 5 mg): Weight loss typically becomes noticeable by week 8–12. Clinical trials showed an average of 5–clinically studied weight loss by this point. Energy levels often improve as nausea subsides.
Week 13–20+ (Dose increases to 7.5–15 mg): Cumulative weight loss accelerates. By week 16, many users report 10–15% body weight reduction. The dose titration schedule allows your body to adjust to each level, minimising side effects.
Months 6–12+ (Maintenance dose): SURMOUNT clinical trial data showed average total weight loss of 15–21% body weight at 72 weeks on the maximum 15 mg dose. This is alongside a reduced-calorie diet and increased physical activity—medication works best combined with lifestyle changes.
Important: Individual results vary significantly. Some people lose weight faster, others more slowly. Use our free GLP-1 weight loss calculator to estimate potential results at different doses based on your starting weight.
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 & UK Access Routes
NHS Access: NICE has approved tirzepatide for specialist weight management services. Access is through tier 3/4 NHS services via GP referral. Availability and waiting times vary by region (ICB)—some areas have waiting lists of several months or longer. Once approved through NHS, the medication is dispensed at standard prescription cost (£9.90 per prescription in England if eligible).
Private Access: Available through GPhC-registered online pharmacies following a brief online clinical consultation with a UK-licensed prescriber. Costs range from approximately £129–£320 per month depending on dose. A standard monthly cost breakdown: 2.5–5 mg around £129–£180, 7.5–10 mg around £180–£240, 12.5–15 mg around £240–£320. Private prescriptions are typically issued within 24–48 hours if clinically appropriate. This route does not require NHS referral or waiting lists.
- 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.
How quickly will I lose weight on Mounjaro?
Weight loss typically becomes noticeable between weeks 8–12 as your dose reaches therapeutic levels. Clinical trials showed average losses of 15–21% body weight over 72 weeks on the maximum dose, but individual timelines vary. Combining the injection with a reduced-calorie diet and physical activity produces the best results.
What is the cost of Mounjaro on the NHS versus private?
Through the NHS, Mounjaro is available at standard prescription cost (£9.90 per prescription in England) but requires specialist referral and may involve waiting lists. Private prescriptions cost £129–£320 per month depending on dose, available within 24–48 hours without NHS referral. Private access is faster but costlier.
How do I get Mounjaro prescribed in the UK?
NHS route: ask your GP for referral to a specialist weight management service (tier 3/4). Private route: complete an online consultation with a UK-licensed prescriber through a GPhC-registered pharmacy. The prescriber will assess your eligibility based on BMI and health factors before issuing a prescription.
Can I use our BMI calculator to check if I might be eligible for Mounjaro?
Yes—use our free BMI calculator on this page to check your current BMI. Mounjaro may be prescribed to adults with a BMI of 30 or above, or 27–29.9 with weight-related health conditions. Your GP or prescriber will make the final eligibility assessment.
What is the dose titration schedule for Mounjaro?
Mounjaro starts at 2.5 mg weekly and increases every 4 weeks: 5 mg, 7.5 mg, 10 mg, 12.5 mg, up to a maximum of 15 mg weekly. This gradual dose titration schedule helps your body adjust and reduces side effects. Your prescriber may adjust the timeline based on your response and tolerance.
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.