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 to Your Body When You Stop Taking Monjaro
When you stop taking Monjaro (tirzepatide), your body undergoes several changes as the medication leaves your system. The most noticeable effect is typically a return of appetite and hunger signals, since the GIP receptor and GLP-1 receptor agonist effects wear off. Weight regain is common without continued lifestyle changes. Understanding what to expect helps you plan ahead and maintain any progress you've achieved. This guide covers the physical, metabolic, and appetite-related changes you may experience after stopping this weekly weight loss injection.
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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.
Physical and Appetite Changes After Stopping Monjaro
Once you stop taking Monjaro, the tirzepatide in your body gradually clears your system over several days. The primary change most people notice is a return of appetite and hunger sensations — often within days to a week. This happens because the medication's dual GIP and GLP-1 receptor agonist effects, which suppress hunger signals and promote satiety, are no longer active.
- Appetite and food cravings typically return to pre-treatment levels
- The feeling of fullness after eating smaller portions may diminish
- You may experience increased desire for foods previously avoided
- Stomach slowing effects stop, returning normal digestion pace
- Energy levels may change as your body readjusts
These changes can happen quite quickly — some people report noticeable appetite increase within 3–7 days of their last injection. The speed and intensity vary between individuals depending on how long you took the medication and your metabolic factors.
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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.
Weight Regain and Maintaining Your Progress
Research shows that weight regain occurs in most people who stop GLP-1 or GIP/GLP-1 medications without making permanent lifestyle changes. On average, people regain approximately 50% of lost weight within the first year after stopping. This doesn't mean your progress is wasted — it reflects the natural metabolic challenge of maintaining weight loss without pharmacological support.
To minimise regain, focus on the habits you've built during treatment: a structured eating pattern, portion awareness from using our free GLP-1 weight loss calculator to understand your journey, continued physical activity, and consistent self-monitoring. Your GP can advise whether stepping down gradually, restarting at a lower dose, or maintaining other weight management strategies suits your circumstances.
- 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 does appetite return after stopping Monjaro?
Most people experience noticeable appetite increase within 3–7 days of stopping Monjaro. The tirzepatide clears your system within days, so GIP and GLP-1 receptor effects cease relatively quickly. Full appetite normalisation may take 2–4 weeks for some individuals.
Will I definitely regain weight after stopping Monjaro?
Weight regain is common but not inevitable. Research shows approximately 50% regain on average without continued lifestyle changes. However, if you maintain the eating habits and activity levels you developed during treatment, regain can be minimised significantly.
Can I restart Monjaro if weight returns?
Yes, restarting is possible following a clinical assessment with a prescriber. Some people use a stepped approach — stopping briefly then restarting at a lower dose. Your prescriber can advise the best approach for your circumstances.
Does stopping Monjaro cause any serious side effects?
Stopping Monjaro itself is not dangerous. You may experience increased hunger, mood changes, or fatigue as your body readjusts, but these are not medical emergencies. If you have type 2 diabetes, inform your GP before stopping as blood sugar management may change.
What should I do to prevent weight regain after stopping?
Maintain the dietary habits and physical activity you developed during treatment. Track your progress using our free progress tracker to stay accountable. Consider working with a dietitian for a structured maintenance plan. Your GP can also discuss whether ongoing weight management support is appropriate for you.
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.