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
When To Increase Your Mounjaro Dosage
Mounjaro (tirzepatide) dosage increases follow a structured 4-week titration schedule set by your prescriber. Your dose typically increases every 4 weeks, starting at 2.5 mg and escalating up to a maximum of 15 mg once weekly. However, the timing and decision to increase depends on your individual tolerance, side effects, and clinical response. Your GP or weight management prescriber will assess whether you're ready to move to the next dose based on how well you've tolerated the current dose and your progress.
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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.
Standard Mounjaro Titration Schedule
Mounjaro follows an established dose titration protocol in the UK. Each dose level lasts a minimum of 4 weeks before escalation is considered. Here's the typical schedule:
- Weeks 1–4: 2.5 mg once weekly (starting dose)
- Weeks 5–8: 5 mg once weekly (first increase)
- 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 onwards: 15 mg once weekly (maximum dose)
Your prescriber may recommend staying at a lower dose if you're experiencing good weight loss and tolerating the medication well. Not everyone needs to reach the maximum 15 mg dose — your prescriber will assess your individual needs and adjust accordingly.
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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.
Signs You May Be Ready for the Next Dose
Your prescriber will consider several factors before increasing your Mounjaro dose. You're typically ready to escalate if you've tolerated the current dose well — meaning side effects like nausea or diarrhoea have settled, and you're not experiencing ongoing gastrointestinal discomfort. If you've noticed good progress in your weight loss journey, your prescriber may recommend continuing at your current dose rather than increasing. Conversely, if you haven't experienced significant nausea or appetite reduction, increasing may be considered to optimise results. Always discuss with your GP or prescriber before changing your dose — they'll use our GLP-1 weight loss calculator and your individual health data to guide the decision.
- 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 minimum interval between dose increases is 4 weeks. Increasing faster is not recommended and may not be approved by your prescriber. The 4-week period allows your body to adjust and helps your prescriber assess tolerance and effectiveness safely. Never increase your Mounjaro dose without explicit guidance from your GP or licensed prescriber.
What if I'm not losing weight at my current Mounjaro dose?
If you're not seeing weight loss progress, discuss this with your prescriber at your next review. They may recommend waiting another 4 weeks, increasing to the next dose, or reviewing your diet and activity levels. Weight loss takes time — clinical trials showed results accumulate over weeks and months. Your prescriber may use our weight loss calculator to assess whether your current dose is appropriate.
What if I get severe side effects when increasing my Mounjaro dose?
If you experience severe side effects after a dose increase — such as persistent vomiting, severe abdominal pain, or signs of pancreatitis — contact your GP or prescriber immediately. You may need to stay at your current dose longer or return to a previous dose. Never continue with a dose that's causing severe side effects without medical guidance.
Is 15 mg the dose everyone reaches on Mounjaro?
No. The maximum licensed dose is 15 mg, but many people achieve good results at lower doses like 5 mg, 10 mg, or 12.5 mg. Your prescriber will determine the most appropriate dose for your weight loss goals and tolerance. Some people plateau at a lower dose and don't need to escalate further.
How do I know if my prescriber will increase my Mounjaro dose?
Your prescriber will review your progress at scheduled appointments (typically every 4 weeks). They'll ask about side effects, appetite changes, weight loss, and how you're managing your diet and activity. If you're tolerating your current dose well and ready to increase, they'll prescribe the next dose level. Always discuss any concerns about dosing at your review appointment. ```
Ready to take control of your weight loss journey?
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