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 Happens After 3 Months on Mounjaro in the UK?
When starting Mounjaro (tirzepatide), most people follow a 4-week dose escalation schedule. After 3 months on treatment, you'll typically be on your maintenance dose, and the medication's effects on appetite and food intake become more consistent. This guide covers what to realistically expect after 3 months, how to access Mounjaro in the UK through NHS and private routes, and what the costs look like. Understanding both the health journey and the practical access routes helps you make informed decisions about weight management treatment in the UK.
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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 Access and Cost in the UK
Private prescription route: If you access Mounjaro through a private online consultation with a UK-licensed prescriber, costs typically range from £150–£320 per month depending on your maintenance dose. A standard 4-week supply (one KwikPen containing four weekly injections) costs around £200–£280 at private pharmacies. Prices vary between providers and may include consultation fees.
NHS route: Mounjaro is available through NHS specialist tier 3 weight management services following NICE approval. NHS access is free at the point of use but requires referral from your GP to a specialist service. Waiting times vary significantly by region—some areas have waiting lists of 6–18 months or longer. You'll need a BMI of 30 or above, or 27–29.9 with weight-related health conditions (such as type 2 diabetes, high blood pressure, or sleep apnoea) to qualify.
After 3 months of consistent use alongside a reduced-calorie diet and increased physical activity, clinical evidence suggests you may see meaningful weight loss results, though individual outcomes vary considerably.
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.
How to Access Mounjaro: NHS vs Private Routes
NHS access: Speak to your GP about referral to your local specialist weight management service (tier 3). Your GP will assess eligibility based on BMI and health conditions. If approved, you'll be added to the service's waiting list and invited for assessment once a slot becomes available.
Private access: You can access Mounjaro immediately through online private prescribing. A UK-licensed prescriber will review your medical history via an online consultation, assess suitability, and issue a prescription if appropriate. Your prescription is then dispensed by a GPhC-registered pharmacy. The entire process typically takes 24–48 hours from consultation to receiving your first KwikPen. Use our GLP-1 weight loss calculator to estimate potential weight loss outcomes at different doses, and track your progress with our free progress tracker once you begin 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.
How much weight can you lose in 3 months on Mounjaro?
Clinical trials showed participants lost an average of 5–8% of their body weight over 12 weeks, though results vary significantly. Use our free GLP-1 weight loss calculator to estimate potential outcomes for your personal situation. Weight loss depends on dose, diet adherence, activity level, and individual metabolism.
What dose of Mounjaro are most people on after 3 months?
Most people follow the standard escalation schedule: 2.5mg weeks 1–4, 5mg weeks 5–8, 7.5mg weeks 9–12, and potentially 10mg from week 13 onwards. After 3 months you'd typically be on 7.5–10mg depending on tolerability and response. Your prescriber adjusts based on side effects and effectiveness.
Is Mounjaro available on the NHS in the UK?
Yes. NICE approved tirzepatide for NHS specialist weight management services. Access is through referral to your local tier 3 service from your GP. NHS provision is free but waiting times vary by region—some areas have significant waiting lists. Private access is faster but costs £150–£320 monthly.
What's the difference between Mounjaro and Wegovy?
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist; Wegovy (semaglutide) is GLP-1 only. Clinical trials suggest Mounjaro may produce slightly higher average weight loss (around 20.9% vs 14.9% at maximum doses), but individual results vary. Both are prescription-only, require clinical assessment, and cost similarly in the private market.
Can I get Mounjaro from my GP without waiting for specialist services?
Mounjaro prescriptions for weight management are typically issued by NHS specialist tier 3 services, not standard GP practices. For faster access, you can use private online prescribing services with a UK-licensed prescriber—usually available within 24–48 hours. Your GP can still provide ongoing support alongside private treatment.
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.