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
Can You Decrease Mounjaro Dose?
Yes, you can decrease your Mounjaro dose, but only under prescriber guidance. Some people reduce their dose if they experience side effects, while others may step back temporarily for medical reasons. Mounjaro (tirzepatide) is a prescription-only injection, and any dose adjustment should be discussed with your GP or the prescriber managing your treatment. This guide explains when dose reduction might be appropriate and what to expect.
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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.
When Dose Reduction Might Be Considered
Mounjaro dose reduction isn't routine, but your prescriber may suggest it in specific situations. If you're experiencing significant side effects—such as severe nausea, persistent vomiting, or stomach pain—a temporary reduction or pause may help your body adjust. Some people also request dose reduction if they've reached their weight loss goals and want to maintain results on a lower dose. Medical reasons like planned surgery, pregnancy planning, or management of other health conditions may also prompt a dose step-down. Your prescriber might also reduce your dose if you're about to switch to another weight loss medication or if you've experienced a serious adverse reaction. The key point is that any dose change must be initiated and monitored by your prescriber—never adjust your Mounjaro KwikPen dose on your own. Your prescriber will weigh up the benefits of continued weight loss support against the burden of side effects and your individual health circumstances.
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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.
How to Discuss Dose Adjustment With Your Prescriber
If you're considering a dose reduction, book an appointment with your GP or the prescriber managing your Mounjaro treatment. Be clear about why you want to reduce—whether it's side effects, reaching your goal weight, or other medical reasons. Bring a record of any side effects you've experienced and when they started, as this helps your prescriber make an informed decision. Don't suddenly stop your Mounjaro or skip doses; stopping abruptly can affect your weight management plan. Your prescriber may suggest a temporary reduction rather than permanent discontinuation, or they might recommend strategies to manage side effects at your current dose instead. Once you've discussed adjustments, your prescriber will explain the plan and monitor you during any changes. Track your progress using our free progress tracker to help you and your prescriber assess how you're responding.
- 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.
What happens if I reduce my Mounjaro dose?
Reducing your dose may decrease weight loss support and increase the risk of weight regain, but it may also reduce side effects. Your prescriber will monitor your response and adjust as needed. The effect depends on your dose level, current weight, and individual metabolism.
Can I skip a Mounjaro injection if I'm having side effects?
You shouldn't skip doses without guidance, as this can disrupt your treatment. Instead, contact your prescriber immediately. They may recommend a temporary dose reduction, strategies to manage side effects, or a planned pause before your next injection.
Is it normal to want to reduce Mounjaro after weight loss?
Yes. Some people maintain their weight loss on a lower maintenance dose, whilst others continue their current dose. This is individual—discuss your goals with your prescriber, who can advise whether dose reduction is appropriate for you.
What's the difference between Mounjaro and Wegovy dose adjustments?
Mounjaro (tirzepatide) has a maximum dose of 15mg weekly, whilst Wegovy (semaglutide) maxes at 2.4mg weekly. Both require prescriber guidance for any dose changes. The dual GIP and GLP-1 mechanism of Mounjaro differs from Wegovy's single GLP-1 pathway.
Can my GP help with Mounjaro dose reduction?
Yes. If your GP prescribed or is monitoring your Mounjaro, they can discuss and manage dose adjustments. If you accessed Mounjaro privately, contact the prescriber who issued your prescription. Always involve a healthcare professional before making changes.
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.