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 Diary: NHS Prescribing in the UK
A Mounjaro diary tracks your experience with tirzepatide treatment — from your first injection through dose titration to ongoing management. In the UK, access to Mounjaro (tirzepatide) is primarily through NHS tier 3 specialist weight management services following NICE approval. Understanding the NHS pathway, eligibility criteria, and what to document throughout your treatment journey can help you make the most of this prescription medication. This guide covers the NHS context for Mounjaro in the UK and what you should expect at each stage.
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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.
NHS Eligibility and Tier 3 Services
Mounjaro is a prescription-only medication available in the UK through NHS specialist weight management services (tier 3) or privately through a licensed prescriber. NICE has approved tirzepatide for NHS use in eligible adults.
NHS eligibility criteria:
- BMI of 30 kg/m² or above, OR
- BMI of 27–29.9 kg/m² with at least one weight-related health condition (type 2 diabetes, prediabetes, hypertension, dyslipidaemia, obstructive sleep apnoea, cardiovascular disease)
- For South Asian, Chinese, Black African, or Black Caribbean adults: lower BMI thresholds may apply (from 27.5 kg/m²)
Access through the NHS requires referral to your local tier 3 service from your GP. These specialist services assess your suitability, manage your treatment, and monitor your progress. Waiting times vary significantly by region. You can calculate your BMI using our free tool to check your eligibility range, though your NHS team will conduct a full assessment.
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: Pathways and Timescales
NHS route: Referral through your GP to a tier 3 weight management service. Assessment, prescription, and monitoring are provided by the NHS. Waiting lists can be lengthy (months to years in many areas). No direct cost to you, but access depends on regional availability and service capacity.
Private route: Online consultation with a UK-licensed prescriber, prescription issued if clinically appropriate, and dispensed by a GPhC-registered pharmacy. Typically available within days to weeks. You pay privately (usually £129–£320+ per month depending on dose). Both routes require clinical assessment — Mounjaro is not available without a prescription, regardless of pathway.
If tracking your Mounjaro experience, our free progress tracker helps you log doses, side effects, and weight changes alongside your NHS or private treatment plan.
- 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 should I include in a Mounjaro diary?
Track your injection date and dose (2.5 mg, 5 mg, etc.), any side effects experienced (nausea, appetite changes), how you felt each week, your weight if monitoring at home, and notes about your appetite or energy levels. Share this information with your NHS prescriber or private healthcare provider at your review appointments — it helps them assess how well you're tolerating tirzepatide.
How long does NHS assessment for Mounjaro take?
NHS assessment timescales vary by region. Initial referral to tier 3 services can take weeks to months depending on waiting lists. Once accepted into the service, assessment may happen within a few weeks, but some areas have significant delays. Contact your local integrated care board (ICB) to ask about expected waiting times in your area.
Can I switch from NHS to private Mounjaro treatment?
Yes, you can switch between NHS and private treatment. However, coordination is important. If you're already receiving NHS treatment, inform your private prescriber. If switching from private to NHS, discuss with your GP about referral to tier 3 services. Your medical history and current dose will inform the transition.
What dose progression should I expect on Mounjaro in the NHS?
NHS prescribing follows the licensed dose titration: starting at 2.5 mg weekly, increasing by 2.5 mg increments every 4 weeks (5 mg, 7.5 mg, 10 mg, 12.5 mg, 15 mg). Your tier 3 team will decide the appropriate pace and maximum dose based on your tolerance, side effects, and response. Clinical trials showed average weight loss of 15–21% of body weight, though individual results vary significantly.
Is Mounjaro available on the NHS everywhere in the UK?
Mounjaro is approved by NICE for NHS use, but availability varies considerably by region and ICB. Some areas have well-resourced tier 3 services; others have limited capacity. Ask your GP whether your local NHS weight management service prescribes Mounjaro, or contact your ICB directly. Private access is more consistent across the UK if NHS access is limited in your area.
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.