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
Should I Go Up A Dose On Mounjaro?
Deciding whether to increase your Mounjaro (tirzepatide) dose is a decision you'll make together with your prescriber, not one you should make alone. Unlike generic weight loss advice, prescription medication dosing follows a structured, individual plan based on your response to treatment and any side effects you're experiencing. Your prescriber will guide you through the dose titration schedule, typically waiting at least 4 weeks at each dose level before considering an increase. Understanding how Mounjaro's dual GIP and GLP-1 mechanism works—and how it differs from alternatives like Wegovy—can help you have a more informed conversation with your healthcare provider about what's right for you.
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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.
Mounjaro Dose Titration Schedule vs Clinical Trial Data
Mounjaro dosing follows a structured escalation plan starting at 2.5 mg once weekly, with increases typically every 4 weeks: 5 mg, 7.5 mg, 10 mg, 12.5 mg, and finally 15 mg as the maximum maintenance dose. The SURMOUNT-1 clinical trial—which tested tirzepatide—showed average weight loss of approximately 15% at 5 mg, 19.5% at 10 mg, and 20.9% at 15 mg over 72 weeks when combined with diet and exercise.
Your prescriber will assess whether you should progress to the next dose based on:
- Your weight loss progress and response to the current dose
- Side effects you're experiencing (nausea, vomiting, diarrhoea)
- Your overall health and any other medications
- Your ability to tolerate the current dose safely
Comparatively, Wegovy (semaglutide, a GLP-1 only agonist) showed average weight loss of approximately 14.9% in the STEP-1 trial, demonstrating similar real-world outcomes despite the different mechanism. The choice between Mounjaro's dual mechanism versus Wegovy's single GLP-1 action depends on individual factors your prescriber will assess.
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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 Your Prescriber May Recommend Staying Or Increasing Your Dose
Your prescriber will keep you on your current dose if you're experiencing good weight loss and tolerating it well. Many people achieve their weight management goals without reaching the maximum 15 mg dose. There's no advantage to increasing if your current dose is working—higher doses aren't "better" if you're already seeing results and feeling well.
Your prescriber may increase your dose if: you're not seeing expected weight loss after 4 weeks, you've tolerated the current dose without significant side effects, and your health profile supports escalation. You should not increase independently—each dose increase is a clinical decision requiring prescriber review. If side effects are limiting (severe nausea, persistent vomiting), your prescriber might hold at the current dose, reduce temporarily, or switch medication entirely. Track your progress using our free progress tracker to share concrete data with your prescriber at review appointments.
- 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 a dose increase if I'm happy with my current weight loss on Mounjaro?
Yes, absolutely. There's no requirement to reach the maximum 15 mg dose. If you're losing weight steadily and tolerating your current dose well, your prescriber may recommend staying where you are. The goal is effective, sustainable weight management with manageable side effects—not reaching the highest possible dose.
How long should I wait before asking to increase my Mounjaro dose?
The standard guidance is to wait at least 4 weeks at each dose level before considering an increase. This allows your body to fully adjust and gives your prescriber accurate data about how well that dose is working for you. Never increase on your own—always discuss with your prescriber.
Is Mounjaro 15 mg more effective than 10 mg for everyone?
Not necessarily. The SURMOUNT trials showed modest additional weight loss at 15 mg compared to 10 mg (20.9% vs 19.5%), but individual responses vary significantly. Some people see excellent results at 10 mg or even lower doses. Your prescriber will assess whether the additional increase offers meaningful benefit for you specifically.
How does Mounjaro dose compare to Wegovy for weight loss?
Mounjaro's dual GIP+GLP-1 mechanism and Wegovy's single GLP-1 mechanism showed similar average weight loss in trials (approximately 15–21% for Mounjaro, 14.9% for Wegovy). Individual results vary widely. Your prescriber will consider your health profile, previous medication responses, and other factors when deciding which is more suitable for you—it's not about which is objectively "better."
What should I do if Mounjaro side effects prevent me from going up to the next dose?
Discuss this with your prescriber immediately. Options include: staying on your current dose if it's working, reducing back down temporarily, switching to a different medication, or trying a slower titration schedule. Severe side effects shouldn't be pushed through—your prescriber can adjust your treatment plan to be both effective and tolerable.
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.