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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Do You Have To Increase Your Mounjaro Dose?
No, you do not have to increase your Mounjaro dose — but your prescriber may recommend escalation based on your individual response and tolerance. Mounjaro (tirzepatide) comes as a once-weekly KwikPen injection, and most people start on the lowest dose of 2.5 mg. Whether you increase depends on how well you're managing side effects, your weight loss progress, and your prescriber's clinical assessment. This guide explains the dose titration process, when increases happen, and what to expect during your Mounjaro treatment in the UK.
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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 Escalation Works
Mounjaro is typically introduced using a dose escalation schedule — not because you must increase, but to help your body adjust to the medication and minimise side effects like nausea and stomach upset. The standard titration is:
- Weeks 1–4: 2.5 mg once weekly (starting dose)
- Weeks 5–8: 5 mg once weekly (first escalation)
- Weeks 9–12: 7.5 mg once weekly
- Weeks 13–16: 10 mg once weekly
- Weeks 17–20: 12.5 mg once weekly
- Week 21+: 15 mg once weekly (maximum dose)
Each dose level is maintained for a minimum of 4 weeks before any increase. Your prescriber may pause or extend the time at a particular dose if you're experiencing significant side effects, managing well, or achieving good weight loss progress. The escalation is not automatic — it's individualised to your response. If you're tolerating your current dose well and losing weight steadily, you may stay at that level rather than increasing further.
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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 Your Prescriber May Not Increase Your Dose
Your prescriber may decide not to increase your Mounjaro dose if:
- You're experiencing significant side effects (nausea, vomiting, constipation) that aren't settling
- You're already achieving your weight loss goals and sustaining results
- You have underlying health conditions that make higher doses less suitable
- You're managing well at your current dose without further escalation needed
- You prefer to stay at a lower dose that feels comfortable
There is no requirement to reach the maximum 15 mg dose — the goal is finding the dose that works best for you, provides good weight loss support, and that you can tolerate comfortably. Some people find their optimal dose at 5 mg or 10 mg and remain on that indefinitely. Track your progress using our free progress tracker to discuss outcomes with your prescriber and decide together whether increasing is right for you.
- 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.
Can I stay on a lower Mounjaro dose permanently?
Yes. Many people remain on lower doses (5 mg, 7.5 mg, or 10 mg) long-term if they're achieving good results and tolerating the medication well. Your prescriber will assess whether your current dose is meeting your weight loss goals and supporting your health. If it is, there's no clinical reason to increase further.
What if I want to stop increasing my Mounjaro dose?
Tell your prescriber. Dose escalation is guided by clinical assessment, but your preferences and tolerance matter. If you're managing well at your current dose and experiencing unpleasant side effects at higher levels, your prescriber may recommend staying where you are or may suggest alternative approaches.
How does Mounjaro dose compare to Wegovy for weight loss?
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist, while Wegovy (semaglutide) is GLP-1 only. Clinical trials suggest Mounjaro may support slightly greater average weight loss — roughly 15–21% body weight versus 15% for Wegovy — though individual results vary significantly. Your prescriber will recommend the most suitable option based on your health profile.
Will I experience side effects when increasing my Mounjaro dose?
Some people notice side effects when stepping up doses, particularly nausea, diarrhoea, or reduced appetite. These typically settle within a few days to a week. If side effects are severe, your prescriber may extend the time at your current dose before increasing or may adjust your approach. This is why dose titration is gradual.
What should I discuss with my prescriber about Mounjaro dose increases?
Discuss your weight loss progress, any side effects you're experiencing, how you're managing your diet and activity levels, and whether you feel ready to increase. Use our GLP-1 weight loss calculator to estimate potential outcomes at different doses, and share that conversation with your prescriber to guide shared decision-making about your treatment plan.
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.