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 Mounjaro?
When you stop taking Mounjaro (tirzepatide), your body undergoes several changes as the medication leaves your system. Appetite typically returns to pre-treatment levels, and weight regain is common if lifestyle habits revert to previous patterns. Understanding what to expect after stopping is important for planning your long-term health strategy. Many people who have benefited from Mounjaro wonder how to maintain their progress once treatment ends — and the answer lies in sustainable diet and activity changes made during treatment. This guide explains the physical and metabolic changes you may experience.
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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 Changes After Stopping Mounjaro Treatment
When you discontinue Mounjaro, the hormone-mimicking effects fade as the medication is cleared from your body, typically within 4–5 weeks. During this period, you may notice appetite increases gradually — the strong satiety signals that Mounjaro provides begin to diminish, and hunger cues return to baseline. Many people report feeling hungrier than they did on treatment, sometimes within days of stopping the final dose.
Weight regain is common but not inevitable. Clinical evidence and real-world experience show that people who regain weight after stopping usually do so because eating habits revert to pre-treatment patterns. Those who maintain the dietary and lifestyle changes adopted during Mounjaro therapy — calorie awareness, portion control, regular physical activity — typically maintain most or all of their weight loss. Your metabolic rate does not significantly decrease; the difference is simply the absence of appetite suppression.
- Stomach sensitivity may resolve — nausea and digestive changes fade
- Energy levels may shift as appetite normalises
- Cravings for previously avoided foods may return gradually
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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
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Accessing Mounjaro and Planning Your Treatment Journey in the UK
Understanding your options for accessing Mounjaro in the UK helps you plan both your treatment and post-treatment strategy. Mounjaro is available through two main routes: specialist NHS tier 3 weight management services (where availability varies significantly by region and waiting lists can be lengthy) and private prescription through GPhC-registered online pharmacies following an online clinical assessment. The cost, convenience, and timeline differ substantially between routes.
When considering Mounjaro or comparing it with alternative options like Wegovy (semaglutide), it's worth understanding the dose titration schedule and whether you plan to continue indefinitely or use it as a defined treatment course. Discussing your long-term goals with your prescriber helps you plan what happens after stopping — whether that's transitioning to maintenance therapy, lifestyle management alone, or exploring alternative approaches. Use our free GLP-1 weight loss calculator to estimate potential outcomes at different doses, and our BMI calculator to track where you stand currently.
- 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 weight regain happen after stopping Mounjaro?
Weight regain varies widely. Some people maintain weight loss for months if lifestyle habits remain stable. Others regain weight within weeks if eating patterns revert to pre-treatment levels. Most regain occurs within 3–6 months if dietary discipline is not maintained. Gradual regain (rather than sudden) suggests lifestyle drift rather than metabolic change.
Can you restart Mounjaro if you gain weight after stopping?
Yes, Mounjaro can be restarted following a new clinical assessment. However, discuss with your prescriber whether continuous therapy or "on-and-off" approaches are appropriate for your individual health situation. Some people benefit from long-term maintenance; others use it for defined periods and rely on lifestyle management between courses.
What's the difference between stopping Mounjaro and stopping Wegovy?
Both are GLP-1-based medications with similar rebound appetite effects when stopped. Mounjaro is a dual GIP+GLP-1 agonist and Wegovy is GLP-1-only, but appetite rebound and weight regain patterns are comparable. The key difference is your prescriber can adjust either based on your response and goals.
How much does Mounjaro cost privately in the UK?
Private Mounjaro costs typically range from £150–£300+ per month depending on dose and provider, as prices vary between GPhC-registered pharmacies. Your dose will determine cost — higher doses (10mg, 15mg) cost more than lower doses (2.5mg, 5mg). Always clarify full cost including any consultation fees before starting treatment.
Is Mounjaro available on the NHS for weight management?
Yes, NICE has approved tirzepatide (Mounjaro) for NHS use, but access is through specialist tier 3 weight management services following GP referral — not routine GP prescription. Availability, waiting times, and eligibility criteria vary significantly by region (ICB). Your GP can refer you if you meet eligibility criteria, but NHS availability in your area should be confirmed first.
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.