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
What Is the Mounjaro Maintenance Dose?
The Mounjaro maintenance dose is 15 mg once weekly — the maximum dose available in the UK. However, not all patients require the full 15 mg dose. Your maintenance dose depends on your individual response and tolerance. Most people reach their maintenance dose by week 17 onwards, after gradually titrating through lower doses. Your prescriber will assess which dose works best for your weight loss goals and side effect profile. Always follow your prescriber's guidance, as maintenance doses are personalised.
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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.
Understanding Mounjaro Dose Titration and Maintenance
Mounjaro dose titration begins at 2.5 mg and increases gradually every 4 weeks if tolerated. The standard escalation pathway 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) → 15 mg (week 21+). However, your maintenance dose may be any of these levels — the 15 mg maximum is not mandatory. Some patients achieve excellent weight loss results at 10 mg or 12.5 mg and choose to remain at that dose. Others tolerate the full 15 mg better. In clinical trials using tirzepatide, patients on the 15 mg maintenance dose lost an average of approximately 21% of their body weight over 72 weeks, though individual results vary significantly. Your GP or prescriber will monitor your progress and side effects to establish your optimal maintenance dose.
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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.
Maintenance Dose vs. Titration Phase: What's the Difference?
Titration is the gradual dose escalation phase — typically weeks 1–20. Maintenance is when you reach a stable dose and continue with the same injection each week. At maintenance, your body has adjusted to the medication and you are taking a consistent dose long-term. Most patients reach maintenance between weeks 17–21, depending on tolerance. Once on maintenance, you continue the same dose each week — there is no further increase unless your prescriber recommends it. You should monitor your weight loss progress, appetite changes, and any side effects during maintenance. Use our free GLP-1 weight loss calculator to estimate potential outcomes at different doses, and track your progress with our progress tracker throughout your weight loss journey.
- 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 15 mg the only Mounjaro maintenance dose?
No. The 15 mg dose is the maximum available, but your maintenance dose can be any level that works for you — 5 mg, 7.5 mg, 10 mg, 12.5 mg, or 15 mg. Your prescriber will determine the optimal dose based on your weight loss results and how well you tolerate the medication.
How long does it take to reach maintenance dose?
Most patients reach their maintenance dose between weeks 17–21, as you increase by one level every 4 weeks starting from the initial 2.5 mg dose. Some people may reach maintenance earlier if they tolerate escalation well.
Can I stay on a lower dose if it's working for me?
Yes. If you are losing weight steadily and tolerating the medication well at 10 mg or 12.5 mg, your prescriber may recommend staying at that dose rather than escalating further. Your maintenance dose is personalised to your health outcomes.
What happens if I experience side effects at my maintenance dose?
Inform your prescriber immediately. They may reduce your dose to a lower maintenance level that you tolerate better, or adjust your dietary approach. Do not reduce or change your dose without clinical guidance.
Does Mounjaro maintenance dose need to be adjusted over time?
Your prescriber will monitor your progress and may adjust your maintenance dose if your weight loss plateau or if side effects change. Regular reviews with your prescriber ensure your dose remains appropriate for 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.