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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Keto and Mounjaro — Accessing and Affording GLP-1 in the UK
Combining a ketogenic diet with Mounjaro (tirzepatide) is becoming an increasingly popular weight loss approach in the UK, but understanding how to access Mounjaro and what it costs is essential before starting. Mounjaro is a prescription-only GLP-1 receptor agonist medication available through both NHS specialist services and private prescription routes, with costs and eligibility varying significantly. This guide explains your options for accessing Mounjaro in the UK, typical costs, and how keto can complement GLP-1 treatment alongside a clinical assessment.
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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 to Access Mounjaro in the UK and What It Costs
Private prescription route: Mounjaro is available through private online prescribing services following a brief online clinical assessment with a UK-licensed prescriber. If deemed clinically appropriate, a prescription is issued and dispensed by a GPhC-registered pharmacy. Private costs typically range from £130 to £280 per month depending on the dose — the starting dose of 2.5mg costs less than the maximum 15mg dose. This route does not require NHS referral and provides faster access than waiting for NHS specialist services.
NHS route: Access through the NHS involves referral to a tier 3 specialist weight management service by your GP. NICE has approved tirzepatide for NHS use, but availability varies significantly by region (Integrated Care Board). NHS waiting lists can extend from several months to over a year in many areas. Once prescribed through the NHS, Mounjaro is typically free at the point of use, though prescription charges apply (£9.90 per item in England as of 2025).
- Private: faster access, flexible choice of provider and dose management
- NHS: free medication but longer waiting times and potential supply variability by region
- Both routes require an assessment of BMI (typically 30+) and health history before prescription
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.
Private vs NHS — Which Route is Right for You?
The private route is faster but carries upfront costs; the NHS route is free but involves significant waiting times. Private online consultations typically take 10–15 minutes and ask about your medical history, current medications, weight, height, and weight loss goals. You'll usually receive a response within 24 hours. If prescribed, your first KwikPen (4-week supply) arrives within 2–3 working days. For keto dieters specifically: Mounjaro works synergistically with low-carb eating by further reducing appetite and food cravings. The medication slows gastric emptying, so combining it with keto may enhance satiety. However, this also means nausea (the most common side effect) may be more pronounced initially on keto — staying hydrated and eating nutrient-dense foods helps. Always inform your prescriber that you're following keto so they can monitor blood sugar and nutrient absorption.
- 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 does Mounjaro cost privately in the UK?
Private Mounjaro costs typically range from £130 to £280 per month depending on your dose. Starting doses (2.5–5mg) are usually cheaper; maximum maintenance doses (15mg) are at the higher end. Prices vary slightly between providers. Most private providers offer flexible monthly or quarterly payment options.
Is Mounjaro available on the NHS in the UK?
Yes — NICE approved tirzepatide (Mounjaro) for NHS use in specialist tier 3 weight management services. However, availability varies by region and waiting times can be very long (sometimes 12+ months). You'll need a GP referral to access NHS services.
Can I use keto while taking Mounjaro?
Yes — keto and Mounjaro can work well together. The medication enhances satiety and reduces cravings, which complements low-carb eating. However, nausea (a common Mounjaro side effect) may be more pronounced initially on keto. Stay well-hydrated, eat nutrient-dense foods, and inform your prescriber that you're following keto so they can monitor your blood sugar and nutrient status.
How do private online Mounjaro consultations work?
You complete a brief online health questionnaire (10–15 minutes) with a UK-licensed prescriber. They review your medical history, weight, BMI, and weight loss goals. If Mounjaro is clinically appropriate, you receive a prescription within 24 hours, dispensed by a GPhC-registered pharmacy with delivery within 2–3 working days.
What's the difference between Mounjaro and Wegovy?
Both are prescription-only weight loss injections available in the UK. Mounjaro (tirzepatide) is a dual GIP and GLP-1 agonist with a starting dose of 2.5mg and maximum of 15mg weekly. Wegovy (semaglutide) is a GLP-1 agonist with a maximum dose of 2.4mg weekly. Clinical trials show similar average weight loss (15–21% body weight), but individual results vary. Discuss with your prescriber which suits you best.
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.