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
What Happens When You Stop Mounjaro?
Stopping Mounjaro (tirzepatide) is a decision that should always be made with your prescriber's guidance. When you stop taking Mounjaro, your body gradually adjusts back to its baseline metabolic state. Weight regain is possible after stopping, though the timeline and amount vary significantly between individuals. This guide explains what to expect when discontinuing Mounjaro in the UK context, including NHS guidance and practical considerations for managing your weight after treatment.
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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.
Weight Regain and the Rebound Effect
Clinical experience and NHS guidance suggest that weight regain can begin within weeks of stopping Mounjaro, though this is not inevitable. The hormone regulation your body developed while taking tirzepatide gradually normalises, meaning appetite signals and feelings of fullness return to pre-treatment levels. This doesn't mean you'll regain all weight lost — many people maintain a significant portion of their weight loss long-term, particularly if lifestyle changes made during treatment are sustained.
- Weight regain typically occurs over months rather than days
- Amount regained varies from minimal to substantial depending on diet, activity level, and individual metabolism
- Continuing reduced-calorie eating and increased physical activity significantly reduces regain risk
- Some people maintain 50–70% of weight lost even after stopping
Your GP or prescriber should discuss your individual risk factors and a transition plan before you stop taking Mounjaro.
Clinically BackedWeight Loss
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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.
NHS Guidance on Stopping Mounjaro Safely
The NHS recommends that you should not stop Mounjaro abruptly without medical guidance. Your prescriber may suggest gradually reducing or stopping based on your individual response and health goals. Stopping Mounjaro is not medically dangerous — unlike some diabetes medications, there is no risk of hypoglycaemia or acute complications from discontinuation. However, a managed transition with your GP or tier 3 specialist service is best practice.
If you experience side effects that are intolerable, contact your prescriber immediately rather than stopping suddenly. If cost or access becomes an issue, discuss alternatives with your GP — you may be eligible for NHS specialist weight management services or may benefit from switching to another licensed weight loss medication like Wegovy (semaglutide).
- 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 restart Mounjaro after stopping it?
Yes, you can restart Mounjaro if clinically appropriate, but you would typically restart at the lowest dose (2.5 mg) and retitrate. This should only be done under prescriber guidance. Restarting is often considered if weight regain is significant and you tolerated the medication previously.
How quickly will I regain weight after stopping Mounjaro?
Weight regain varies individually. Some people notice changes within 2–4 weeks; others maintain weight for months. The rate depends on diet, physical activity, metabolism, and how much lifestyle change you've embedded during treatment. Sustaining healthy habits reduces regain significantly.
Will my appetite return to what it was before Mounjaro?
For most people, appetite gradually returns toward baseline over weeks to months. However, many people find their appetite doesn't fully return to pre-treatment levels, especially if they've maintained dietary changes and increased physical activity during treatment.
What should I do to prevent weight regain when stopping Mounjaro?
Work with your GP or a dietitian to develop a transition plan before stopping. Focus on maintaining the dietary changes and physical activity habits you developed during treatment. Our GLP-1 weight loss calculator and free progress tracker can help you monitor changes and stay motivated as you transition off medication.
Is stopping Mounjaro safe?
Yes, stopping Mounjaro is medically safe — there are no dangerous withdrawal effects or acute complications. However, it should be discussed with your prescriber beforehand so you can plan for potential weight regain and ensure you have ongoing support for weight management.
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.