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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Why Is Mounjaro Going Up — Understanding Dose Titration
If you've been prescribed Mounjaro (tirzepatide) in the UK, your dose will gradually increase over several weeks. This is called dose titration, and it's a normal, essential part of treatment. Rather than starting at the maximum dose, your prescriber increases your injection strength every four weeks to help your body adjust and find the dose that works best for you. This approach helps minimise side effects whilst building up to the therapeutic dose. Understanding why Mounjaro doses go up helps you feel more confident about your treatment plan.
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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
Mounjaro comes in five dose strengths, and you'll typically progress through them over 16–20 weeks. You start at 2.5 mg for the first four weeks, then move to 5 mg for weeks 5–8. If your prescriber decides it's appropriate, you then escalate to 7.5 mg, then 10 mg, 12.5 mg, and finally 15 mg — the maximum maintenance dose. Each dose is a once-weekly KwikPen injection. Your prescriber will not increase your dose unless you've been on your current dose for at least four weeks. This gradual approach allows your body to adapt and helps your prescriber assess how well the medication is working for you. If you experience significant side effects, your prescriber may slow the titration schedule or keep you on a lower dose that works better for your individual health.
- Week 1–4: 2.5 mg (starting/adjustment dose)
- Week 5–8: 5 mg (first maintenance dose)
- Week 9–12: 7.5 mg (escalation)
- Week 13–16: 10 mg (further escalation)
- Week 17–20: 12.5 mg to 15 mg (maximum 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.
Why Your Prescriber Increases Mounjaro Gradually
Gradual dose increases serve several important purposes. First, they give your body time to adjust to the medication and minimise nausea, which is the most commonly reported side effect. Second, they allow your prescriber to assess your individual response — how much weight you're losing, how well you're tolerating the injection, and whether you're experiencing any concerning side effects. Third, they help you understand which dose level works best for your personal health goals. Some people achieve excellent results at 5 mg or 7.5 mg and choose not to escalate further. Others progress to 15 mg for maximum effect. Use our free GLP-1 weight loss calculator to explore potential outcomes at different doses. Your prescriber will also discuss whether you need to progress to each new dose, or whether your current dose is already helping you achieve your goals.
- 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.
Does my Mounjaro dose have to go up every four weeks?
No. Your prescriber will only increase your dose if it's appropriate for your health. If you're achieving good results at your current dose, or if you're experiencing side effects, your prescriber may recommend staying on the same dose rather than escalating. Dose progression is personalised to your individual needs.
What if I can't tolerate a higher Mounjaro dose?
Tell your prescriber immediately. They can keep you on a lower dose that works better for you, or slow down the titration schedule. Many people achieve effective weight loss on 5 mg or 7.5 mg. Your comfort and safety matter — there's no pressure to reach 15 mg.
How long does Mounjaro titration take?
Standard titration typically takes 16–20 weeks to reach maximum dose (15 mg), spending four weeks on each dose level. However, your prescriber may adjust this timeline based on your individual response and tolerability.
Can I skip doses during titration?
No. Never skip a scheduled dose. If you miss a dose by more than four days, skip it and continue your regular schedule the next week. Missing or skipping doses disrupts the titration process and your treatment plan.
Is Mounjaro dose titration different on the NHS?
The dose titration schedule is the same regardless of whether you access Mounjaro through NHS specialist services or a private prescription. All prescribers in the UK follow MHRA-approved dosing guidance, starting at 2.5 mg and escalating every four weeks. ```
Ready to take control of your weight loss journey?
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