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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Best Mounjaro for Weight Loss in the UK
Mounjaro (tirzepatide) is a prescription-only weight management injection now approved by NICE for NHS use in the UK. The "best" Mounjaro approach depends on your individual health, weight, and goals — there's no one-size-fits-all solution. This guide explains NHS eligibility criteria, how Mounjaro works as a dual GIP and GLP-1 receptor agonist, typical dose ranges, and how to access it through the NHS or private prescribing in the UK. Our GLP-1 weight loss calculator can help you estimate potential results 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.
NHS Eligibility and Getting Mounjaro Prescribed
To access Mounjaro through the NHS, you typically need to meet specific criteria. You may be eligible if you have a BMI of 30 kg/m² or above, or a BMI of 27–29.9 kg/m² alongside at least one weight-related health condition such as type 2 diabetes, prediabetes, high blood pressure, abnormal blood fats, obstructive sleep apnoea, or cardiovascular disease. For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower thresholds — eligibility may begin at BMI 27.5 or above.
NICE approved tirzepatide (Mounjaro) for use within NHS specialist weight management services in 2024. However, access is through tier 3 specialist weight management services, not standard GP prescription. You'll typically need a referral from your GP, though availability and waiting times vary significantly by region and integrated care board (ICB). Many areas have extended waiting lists. If you're considering Mounjaro, discuss eligibility with your GP first.
Clinically BackedWeight Loss
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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 Doses and Dose Titration
Mounjaro is supplied in a convenient KwikPen pre-filled device with once-weekly injections. Treatment starts at 2.5 mg per week, increasing gradually to find your effective dose. The standard dose progression is: 2.5 mg (weeks 1–4), 5 mg (weeks 5–8), 7.5 mg (weeks 9–12), 10 mg (weeks 13–16), 12.5 mg (weeks 17–20), and 15 mg (week 21+, maximum dose). Each dose level is maintained for at least 4 weeks before increasing. Clinical trials showed that doses of 10 mg and 15 mg produced the greatest average weight loss — approximately 19.5% and 20.9% of body weight respectively. However, individual results vary considerably, and your prescriber will determine the best dose for you alongside a reduced-calorie diet and increased physical activity.
- 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.
Is Mounjaro better than Wegovy?
Both Mounjaro (tirzepatide) and Wegovy (semaglutide) are effective weight loss medications approved for NHS use. Mounjaro is a dual GIP and GLP-1 agonist, while Wegovy acts on GLP-1 alone. Clinical trials showed Mounjaro produced slightly higher average weight loss, but individual results vary significantly. Your prescriber will recommend the most suitable option based on your health profile, medical history, and personal circumstances. Neither is universally "better" — the best choice is the one appropriate for you.
Can I get Mounjaro on the NHS in the UK?
Yes, NICE approved Mounjaro (tirzepatide) for NHS use in weight management services in 2024. However, access is through specialist tier 3 weight management services, not routine GP prescription. You'll need a referral from your GP and must meet eligibility criteria (BMI ≥30, or 27–29.9 with weight-related health conditions). Availability and waiting times vary by region. Contact your GP to discuss referral and local access pathways.
What's the maximum Mounjaro dose in the UK?
The maximum licensed Mounjaro dose is 15 mg once weekly. Your prescriber will start you at 2.5 mg and increase gradually (every 4 weeks minimum) to find your effective dose. Most people achieve good results at 10–15 mg, but some respond well at lower doses. The right dose is individual — your prescriber will assess your response and tolerability before recommending dose increases.
How does Mounjaro compare to other weight loss injections available in the UK?
Three GLP-1/GIP medications are currently licensed for weight management in the UK: Mounjaro (tirzepatide, once weekly), Wegovy (semaglutide, once weekly), and Saxenda (liraglutide, once daily). Mounjaro's dual mechanism may offer slightly higher weight loss on average, but Wegovy and Saxenda are also effective. Use our BMI calculator to assess your starting point, and discuss which medication suits your lifestyle and health needs with your prescriber.
What happens if Mounjaro doesn't work for me?
If Mounjaro isn't producing desired results at maximum dose, or you experience limiting side effects, your prescriber may suggest alternative approaches: pausing and restarting, switching to a different GLP-1 medication (such as Wegovy), increasing lifestyle interventions, or exploring other weight management options. Never stop Mounjaro abruptly without medical guidance. Track your progress using our free progress tracker and discuss any concerns with your prescriber regularly.
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.