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 Much Does Mounjaro Increase By During Treatment?
Mounjaro (tirzepatide) doesn't start at its full dose. Instead, your prescription increases gradually over several weeks in what's called a titration schedule. Each dose step increases by specific amounts designed to help your body adjust and minimise side effects. Understanding this schedule helps you know what to expect at each stage of treatment. Use our free GLP-1 weight loss calculator to see how different doses may affect your potential weight loss outcomes.
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Calculate Your BMI Instantly
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 Titration Schedule — Weekly Dose Increases
Mounjaro increases in a step-by-step pattern over approximately 16–20 weeks. Here's how the dose progression works:
- Weeks 1–4: 2.5 mg — starting dose to allow your body to adjust
- Weeks 5–8: 5 mg — first increase (2.5 mg rise)
- Weeks 9–12: 7.5 mg — second increase (2.5 mg rise)
- Weeks 13–16: 10 mg — third increase (2.5 mg rise)
- Weeks 17–20: 12.5 mg — fourth increase (2.5 mg rise)
- Week 21+: 15 mg — maximum maintenance dose (2.5 mg rise)
Each increase happens every 4 weeks minimum. Your prescriber may pause your dose at any level if you're experiencing side effects or seeing good results. Not everyone reaches the 15 mg maximum — many people achieve their weight loss goals at lower doses like 5 mg, 7.5 mg, or 10 mg.
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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 Does Mounjaro Increase Gradually?
Gradual dose increases serve several important purposes. Lower starting doses reduce initial nausea and stomach upset, which are common when first taking GLP-1 medications. Your body has time to adapt to each dose level before it increases. This titration approach also helps your prescriber identify the lowest effective dose for you — meaning you get results with the fewest side effects. If you experience persistent nausea or other side effects at any dose, your prescriber may keep you at that level longer or recommend staying there as your maintenance dose. Use our BMI calculator to track how your weight changes at each dose increase.
- 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 skip directly to a higher Mounjaro dose instead of titrating up?
No. The 4-week titration schedule is standard and important for safety. Starting at 2.5 mg allows your body to adjust gradually, reducing the risk of severe side effects. Jumping to a higher dose increases the likelihood of nausea, vomiting, and stomach issues. Your prescriber will follow the approved titration protocol.
What if I experience bad side effects during Mounjaro titration?
Tell your prescriber immediately. You don't have to increase to the next dose if you're struggling with side effects. Many people stay on 5 mg or 7.5 mg as their maintenance dose and still see significant weight loss. Your prescriber may also recommend dose adjustment strategies like taking anti-nausea medication or adjusting your diet temporarily.
Does each 2.5 mg Mounjaro increase mean proportionally more weight loss?
Not necessarily. Weight loss isn't linear across doses. Clinical trials showed that 5 mg produced ~15% average weight loss, while 10 mg and 15 mg produced 19.5% and 20.9% respectively — the increases become smaller at higher doses. Individual results vary significantly, and some people see their best results at lower doses.
How long am I on Mounjaro before reaching the full 15 mg dose?
If you increase every 4 weeks without delays, you'll reach 15 mg at around week 21–24. However, many people pause titration earlier if they're happy with results, side effects develop, or their prescriber recommends staying at a lower maintenance dose long-term.
Is Mounjaro dose titration the same for everyone in the UK?
The standard NHS and private prescribing protocol follows the same 4-week titration schedule shown above. However, individual variation is normal. Your prescriber may adjust timing based on your side effect profile, weight loss progress, and overall health. Always discuss your specific schedule with your prescriber.
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.