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
Can I Stay On 2.5mg Mounjaro Permanently?
The short answer is: staying on 2.5mg Mounjaro long-term is generally not recommended and is not how tirzepatide is prescribed in the UK. The 2.5mg dose is specifically a starting or adjustment dose intended to be used for 4 weeks before stepping up to maintenance levels. Your prescriber will typically increase your dose every 4 weeks to reach a therapeutic dose of 5mg or higher, depending on your individual response and tolerance. Understanding the dose titration schedule and why escalation matters is important for getting the most from this medication.
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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.
How Mounjaro Dose Titration Works in the UK
Mounjaro is prescribed using a dose titration schedule, which means your dose gradually increases over time. The 2.5mg KwikPen is the starting dose only and is typically used for weeks 1–4. After 4 weeks, your prescriber will usually escalate you to 5mg for weeks 5–8, with further increases to 7.5mg, 10mg, 12.5mg, and up to 15mg depending on your response.
- Why escalation matters: Clinical trial data (SURMOUNT-1) showed that higher doses produced greater average weight loss — 5mg showed ~clinically studied weight loss, 10mg showed ~19.5%, and 15mg showed ~20.9%.
- Individual tolerance: Some people experience nausea or side effects at starting doses, so staying on 2.5mg for an extra 4–8 weeks may be discussed with your prescriber for tolerance reasons.
- Prescription requirement: Every dose change requires prescriber review and a new prescription through your NHS specialist service or private provider.
Staying indefinitely on 2.5mg would mean you're not reaching a therapeutic maintenance dose, which reduces the potential benefit of the medication.
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.
When Staying on 2.5mg Might Be Discussed
In rare cases, you and your prescriber might agree to stay on 2.5mg longer if you're experiencing significant side effects such as persistent nausea, vomiting, or stomach pain at higher doses. However, this would typically be reviewed every 4 weeks, not as a permanent plan. Some patients also find their weight loss plateaus before reaching higher doses, but this doesn't mean staying on 2.5mg indefinitely — it means discussing with your prescriber whether further escalation is appropriate or whether you should continue at your current therapeutic dose.
If you're on Mounjaro through an NHS specialist service (tier 3 weight management), your prescriber will monitor your progress and adjust your plan based on your individual health needs. If you're prescribed privately following an online clinical assessment, your prescriber will also review your dose at regular intervals. Use our free GLP-1 weight loss calculator above to estimate potential outcomes at different doses and understand the importance of reaching a therapeutic level.
- 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 2.5mg Mounjaro an effective weight loss dose?
No — 2.5mg is a starting dose only, not a therapeutic maintenance dose. It's designed for tolerance in your first 4 weeks. Clinical trials showed meaningful weight loss occurred at higher doses (5mg and above), alongside a reduced-calorie diet and increased physical activity. Your prescriber will plan to escalate you.
Can I request to stay on 2.5mg instead of increasing?
You can discuss this with your prescriber if you're struggling with side effects. However, staying on 2.5mg indefinitely is unlikely to deliver the weight loss benefits Mounjaro is licensed for. Your prescriber will review your progress every 4 weeks and adjust based on your tolerance and response.
What's the difference between starting and maintenance doses of Mounjaro?
The 2.5mg dose (weeks 1–4) is for your body to adapt. Maintenance doses are typically 5mg, 7.5mg, 10mg, 12.5mg, or 15mg — reached by increasing every 4 weeks. Staying on 2.5mg long-term bypasses the titration schedule and reduces the medication's intended effect.
How long does it take to reach the maximum Mounjaro dose?
If you increase every 4 weeks as planned, it takes approximately 20 weeks (5 months) to reach 15mg. However, many people stabilise at lower maintenance doses like 5mg or 10mg, depending on their individual response and tolerance.
Can I stay on Mounjaro long-term once I reach my goal weight?
That depends on individual factors and NHS or private prescriber guidance. Some people continue at a maintenance dose to prevent weight regain, while others may stop treatment. Your prescriber will discuss sustainability and whether ongoing treatment aligns with your health goals.
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.