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
How Does Increasing Your Mounjaro Dose Work?
Mounjaro (tirzepatide) is prescribed using a gradual dose escalation schedule in the UK. Your prescriber will increase your dose in steps over several weeks to help your body adjust and minimise side effects. Understanding how dose increases work, why they happen, and what to expect is essential for managing your treatment safely and effectively.
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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.
The Mounjaro Dose Titration Schedule
Mounjaro uses a structured titration schedule where doses increase every 4 weeks, beginning at 2.5 mg and potentially reaching a maximum of 15 mg per week. Each Mounjaro KwikPen contains a 4-week supply (4 weekly injections). Your prescriber will assess your progress and tolerability before deciding whether to increase to the next dose step.
- Weeks 1–4: 2.5 mg (starting dose)
- Weeks 5–8: 5 mg (first escalation)
- Weeks 9–12: 7.5 mg
- Weeks 13–16: 10 mg
- Weeks 17–20: 12.5 mg
- Week 21+: 15 mg (maximum dose)
You must stay on each dose for at least 4 weeks before increasing. If you're experiencing significant side effects or poor tolerability, your prescriber may pause dose escalation or keep you on a lower maintenance dose long-term, which is clinically appropriate.
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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 and Why Your Prescriber May Adjust Your Dose
Your prescriber reviews your weight loss progress, side effects, and overall tolerability at each step. If you're managing well and showing good progress, they may proceed with the scheduled increase. If side effects are severe—persistent nausea, vomiting, or stomach pain—they may delay escalation or keep you on a lower dose. Some patients reach their target weight loss on 5 mg or 7.5 mg and don't need to progress to 15 mg.
Clinical trial data shows that higher doses of tirzepatide (10 mg and 15 mg) produce greater average weight loss than lower doses, but individual responses vary significantly. Your GP or prescriber will personalise your treatment based on your health goals, tolerability, and response.
Track your weight loss progress using our free progress tracker to help your prescriber assess whether dose escalation is appropriate for you. Calculate your BMI at each step using our free BMI calculator to monitor how your weight category changes as your treatment progresses.
- 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 increase my Mounjaro dose faster than 4 weeks?
No. The 4-week minimum between doses is standard clinical practice and helps your body adjust safely. Faster escalation increases side effect risk without improving safety or outcomes. Your prescriber will not recommend accelerating the schedule.
What happens if I can't tolerate a dose increase?
Tell your prescriber immediately. They can pause escalation, reduce you back to the previous dose, or keep you on a lower maintenance dose indefinitely. Many people achieve good weight loss on 5 mg or 7.5 mg—the maximum dose isn't required for everyone.
How do I know if my Mounjaro dose is working?
Your prescriber will measure your weight and BMI at each step. Clinical trials show average weight loss of approximately 15–21% over 72 weeks depending on the dose, but individual results vary. If you're not seeing progress after 12–16 weeks, discuss this with your prescriber.
Is 15 mg always the best dose?
No. Research shows that 15 mg produces the greatest average weight loss, but some patients achieve their target weight loss on lower doses. Your prescriber will recommend the dose that balances effectiveness with tolerability for your individual situation.
What should I do if I miss a dose during titration?
If you miss an injection, take it within 4 days and continue your normal schedule. If more than 4 days have passed, skip that dose and take your next dose on the scheduled day. Never take a double dose. Allow at least 72 hours between injections.
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.