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 to Your Body When You Stop Taking Mounjaro?
When you stop taking Mounjaro (tirzepatide), your body gradually readjusts as the medication leaves your system. Most people experience weight regain, particularly if dietary and lifestyle changes are not maintained. Understanding what to expect during this transition is important for managing your health effectively. Your GP can provide personalised guidance on stopping the medication safely and maintaining any weight you've lost.
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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.
Understanding Weight Regain After Stopping Mounjaro
Mounjaro works by activating GIP and GLP-1 hormone pathways, which suppress appetite and help regulate blood sugar. Once you stop taking tirzepatide, these effects gradually diminish over several days to weeks. Research shows that people often regain a significant portion of lost weight within months if they return to previous eating patterns.
- Weight typically begins to return within 1–2 weeks of stopping
- Average regain is 50% of lost weight within 6 months without ongoing lifestyle changes
- Appetite and food cravings often return to pre-treatment levels
- Blood sugar control may worsen if type 2 diabetes is present
The extent of regain depends heavily on whether you maintain the reduced-calorie diet and increased physical activity established during treatment. Those who continue structured eating patterns and exercise typically experience slower and less severe weight regain.
Clinically BackedWeight Loss
No appointments. No waiting rooms. Just care — from a UK-regulated online pharmacy.
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 and Safe Stopping
If you're taking Mounjaro on the NHS through a tier 3 specialist weight management service, your healthcare team will discuss stopping plans with you before treatment ends. NICE guidance recommends continuing healthy eating and activity habits to sustain results. Your GP should monitor your weight, blood pressure, and blood sugar levels (if diabetic) in the weeks after stopping.
- Do not stop abruptly — discuss timing with your prescriber
- Plan dietary and exercise strategies before stopping
- Request follow-up appointments to support maintenance
- Track your weight using a progress tracker to identify early regain
- Consider whether restarting may be appropriate if weight regain is rapid
- 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.
How quickly do you regain weight after stopping Mounjaro?
Weight regain typically begins within 1–2 weeks. Most people regain approximately 50% of their lost weight within 6 months if they return to previous eating habits. Those maintaining dietary changes experience slower regain. Individual timelines vary significantly based on adherence to lifestyle changes.
Do your hunger levels return to normal after stopping Mounjaro?
Yes. Appetite-suppressing effects diminish over several days to weeks as the medication leaves your system. Hunger and food cravings typically return to pre-treatment levels. Some people find eating habits gradually shift back to previous patterns without the medication's appetite control.
Is it safe to stop Mounjaro suddenly?
You should not stop suddenly without discussing it with your prescriber or GP. They can advise on a safe stopping timeline and help you plan lifestyle strategies to minimise weight regain. Abrupt cessation may lead to rapid appetite return and blood sugar destabilisation if you have type 2 diabetes.
Can you restart Mounjaro if you regain weight after stopping?
Potentially, yes — but this requires a new clinical assessment and prescriber consultation. Restarting is not automatic and depends on your current BMI, health status, and NHS or private availability. Your GP can discuss whether restarting is appropriate for your situation.
What should you do to prevent weight regain after stopping Mounjaro?
Maintain the reduced-calorie diet and increased physical activity established during treatment. Monitor your weight regularly using a progress tracker. Stay in contact with your GP or dietitian. Some people benefit from continued support through NHS weight management services or community programmes.
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.