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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Should You Stay On 2.5Mg Mounjaro Or Escalate Your Dose?
Many adults starting Mounjaro begin on the 2.5mg starter dose, but this is designed as an adjustment phase — not a long-term maintenance dose. Whether you should stay on 2.5mg Mounjaro or escalate depends on your individual response, side effects, and health goals. This guide explains the clinical evidence, compares Mounjaro with Wegovy, and outlines what prescribers typically recommend. Remember, your prescriber will assess what's right for you personally following your clinical assessment and ongoing monitoring.
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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.
Mounjaro Dose Escalation: Clinical Guidance And Trial Data
Mounjaro is designed with a stepwise dose titration schedule. The 2.5mg dose is an adjustment phase lasting weeks 1–4. According to the SURMOUNT clinical trial, the 2.5mg dose produced modest weight loss, but greater results were seen at higher doses. The standard schedule escalates to 5mg (weeks 5–8), then increases every 4 weeks up to the maximum 15mg, provided the dose is tolerated.
Most adults continue escalating unless they experience side effects that prevent further increases. Staying on 2.5mg long-term is typically recommended only if:
- Higher doses cause intolerable gastrointestinal side effects (nausea, diarrhoea, vomiting)
- You have reached your weight loss goal and maintain it effectively
- Clinical factors mean your prescriber advises against escalation
In the UK, your tirzepatide prescription comes via a Mounjaro KwikPen — each pen contains four 2.5mg doses. Your prescriber will discuss whether escalation is appropriate at your 4-week review.
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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.
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Mounjaro Versus Wegovy: Different Mechanisms, Different Escalation Pathways
A key difference when comparing Mounjaro vs Wegovy is how each medication works. Mounjaro is a dual GIP and GLP-1 receptor agonist — it activates two hormone pathways, potentially producing stronger appetite suppression. Wegovy is a GLP-1-only agonist. This mechanistic difference can affect how well each works for individual patients.
In the SURMOUNT trials, participants on 15mg Mounjaro lost approximately 20.9% body weight on average. Wegovy's STEP trials showed approximately 14.9% average weight loss at the maximum 2.4mg dose. However, these are clinical trial averages — individual results vary significantly. Your prescriber will assess whether Mounjaro or Wegovy is more suitable based on your health profile, medical history, and response to treatment. Both require an NHS NICE approval pathway or private UK prescription following a clinical assessment.
- 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 a permanent dose?
No. The 2.5mg dose is a starter adjustment phase lasting 4 weeks. Most patients escalate to 5mg at week 5, with further increases every 4 weeks as tolerated. Staying on 2.5mg long-term is usually only recommended if higher doses cause intolerable side effects or you've achieved your weight loss goal and maintain it successfully.
What's the difference between Mounjaro and Wegovy?
Mounjaro (tirzepatide) is a dual GIP+GLP-1 agonist; Wegovy (semaglutide) is GLP-1-only. Mounjaro's dual mechanism may produce stronger effects. Maximum doses differ: Mounjaro reaches 15mg weekly, Wegovy reaches 2.4mg weekly. Clinical trials showed Mounjaro produced slightly higher average weight loss, but individual results vary. Your prescriber assesses which suits you best.
Can I stay on 2.5mg Mounjaro if I'm happy with it?
You can discuss this with your prescriber. If the 2.5mg dose is controlling your appetite well, you've reached your target weight, and side effects are minimal, your prescriber may agree to maintain it. However, the standard protocol involves escalating every 4 weeks if tolerated. This decision is individualised based on your response and health goals.
When should I escalate from 2.5mg to 5mg Mounjaro?
The standard schedule moves from 2.5mg (weeks 1–4) to 5mg (weeks 5–8). You escalate at week 5 unless side effects prevent it. Your prescriber will review your response at your 4-week check. If gastrointestinal side effects are severe, you may delay escalation. Use our GLP-1 weight loss calculator to estimate potential results at different doses.
Do side effects improve if you stay on 2.5mg longer?
Commonly, yes. Nausea, diarrhoea, and constipation often improve within 2–3 weeks as your body adjusts. If side effects are manageable, your prescriber may suggest staying on 2.5mg for an extra week or two before escalating. However, side effects may re-occur at higher doses. Staying hydrated and eating small, frequent meals helps. Discuss timing with your prescriber.
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