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
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What Happens When You Stop Taking Mounjaro?
If you're considering stopping Mounjaro (tirzepatide), it's important to understand what happens after you come off the medication. Many people experience weight regain after stopping, particularly if lifestyle changes aren't maintained. This guide explains the physical and practical aspects of coming off Mounjaro in the UK, and why medical supervision during this transition is essential. Always discuss stopping Mounjaro with your prescriber — do not stop abruptly without guidance.
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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.
Weight Regain and What the Evidence Shows
Clinical evidence suggests that weight regain is common after stopping GLP-1 and GIP/GLP-1 medications like Mounjaro. In the SURMOUNT trials, participants who stopped tirzepatide regained approximately two-thirds of the weight they had lost within one year — though individual experiences vary significantly.
This happens because:
- Appetite hormones return to pre-medication baseline levels
- The appetite-suppressing effects wear off within days to weeks
- Your body's hunger signals normalise, which may feel intense initially
- Without continued dietary and physical activity changes, weight typically returns
However, if you've made sustained lifestyle changes during Mounjaro treatment — including reduced-calorie eating patterns and regular physical activity — weight regain may be less severe. This is why your GP or prescriber may recommend a structured transition plan rather than simply stopping.
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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.
Managing the Transition and Side Effects
When you stop Mounjaro, side effects like nausea and digestive changes typically resolve within days to weeks as the medication leaves your system. However, increased appetite and food cravings may become noticeable, sometimes quite suddenly. This is a natural physiological response, not a failure on your part.
To manage this transition effectively, consider: maintaining the dietary and exercise habits you've built, gradually increasing calorie intake rather than reverting to previous patterns, staying hydrated and sleeping well (both support appetite regulation), and seeking support from your GP or a registered dietitian. Some people find it helpful to track their progress using a weight tracker to monitor gradual changes rather than focusing on daily fluctuations. Your prescriber may suggest other weight management strategies during this period, including behaviour support or referral to NHS tier 3 weight management services for ongoing specialist guidance.
- 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.
Will I regain all the weight I lost after stopping Mounjaro?
Not necessarily. Evidence suggests people regain approximately two-thirds of lost weight on average — but individual outcomes vary significantly. If you've maintained the dietary and lifestyle changes made during treatment, regain is typically less severe. Your GP can help create a transition plan to support sustained weight management.
How long does it take for appetite to return to normal after stopping Mounjaro?
Appetite typically increases noticeably within days to weeks after stopping, as GIP and GLP-1 levels return to baseline. The intensity of increased appetite varies between individuals. This is a normal physiological response, not a personal failure. Managing this transition with professional support helps many people maintain their progress.
Can I restart Mounjaro if I come off it?
Yes, Mounjaro can be restarted if medically appropriate. However, this requires a new clinical assessment by your prescriber, and you'll restart from the lowest dose (2.5 mg). Discuss long-term weight management strategies with your GP rather than viewing Mounjaro as a temporary fix — it's often used as part of ongoing treatment.
What's the difference between stopping suddenly versus gradually reducing Mounjaro?
Stopping suddenly typically causes rapid return of appetite within days. Gradual reduction (tapering) is not standard practice with Mounjaro, as it doesn't reduce side effects significantly. Your prescriber will advise the best approach for you, which usually means stopping and managing the transition through diet and lifestyle support.
Should I see my GP before stopping Mounjaro?
Yes, always consult your prescriber before stopping. They can assess your health status, discuss what to expect, arrange appropriate support during the transition, and explore whether continuing treatment or alternative strategies might be suitable. Never stop prescription medication without medical guidance.
Ready to take control of your weight loss journey?
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