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
Do You Put Weight Back On After Stopping Mounjaro?
Many people wonder what happens to their weight after stopping Mounjaro (tirzepatide). The honest answer is that weight regain is common but not inevitable. Without the medication's appetite-suppressing effects, your body's hunger signals return to their previous levels, making it easier to regain weight unless you've established lasting lifestyle changes. NHS guidance emphasises that weight loss medications work best as part of a long-term strategy combining diet, physical activity, and behaviour change—not as standalone solutions. Understanding what to expect after stopping, and having a maintenance plan in place, significantly improves your chances of keeping weight off.
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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.
What the NHS and Clinical Evidence Tell Us
Clinical data shows weight regain after stopping GLP-1 and GIP/GLP-1 medications is real but manageable. In the SURMOUNT trials, when participants stopped Mounjaro, weight regain occurred over several months—on average, people regained approximately 50% of their lost weight within one year of stopping treatment. However, this varies significantly based on individual factors including lifestyle changes during treatment, diet adherence, physical activity levels, and underlying metabolic health.
The NHS tier 3 weight management services recommend that stopping Mounjaro should never be abrupt without a structured plan. Your prescriber will discuss a maintenance strategy before you finish treatment. This typically involves:
- Transitioning to sustainable dietary habits established during treatment
- Maintaining increased physical activity levels
- Ongoing behaviour change support
- Regular GP monitoring of weight and metabolic markers
- Discussing whether extended treatment or periodic "top-up" doses may benefit you
Unlike some weekly weight loss injection approaches, Mounjaro's effects diminish gradually as your body clears the medication from your system—usually within 4–5 weeks after your final dose. This gives time to adjust lifestyle habits with medical support.
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.
Managing Weight After Treatment: NHS Approach
The key to keeping weight off after stopping Mounjaro is maintaining the lifestyle changes you made during treatment. Weight loss while on medication happens alongside reduced calorie intake and increased activity—these habits must continue afterward. Your GP or NHS weight management service can help you develop a formal maintenance plan before you stop treatment.
Several options exist: some people benefit from continuing Mounjaro long-term on a lower maintenance dose; others may transition to alternative weight loss approaches including ongoing structured weight management programmes, community support groups, or digital tools like our free progress tracker to monitor your weight trends. The NHS increasingly recognises that for many people, particularly those with significant weight loss or underlying metabolic conditions, ongoing treatment may be necessary rather than one-off intervention. Having this conversation with your prescriber well in advance of stopping helps ensure you're not left without support.
- 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 definitely put weight back on after stopping Mounjaro?
Weight regain is common but not inevitable. Clinical trials show approximately 50% of lost weight is regained on average within a year after stopping, but this varies greatly depending on whether you maintain the lifestyle changes you made during treatment. Sustained dietary habits and physical activity significantly reduce regain risk.
How quickly do you regain weight after stopping Mounjaro?
Weight regain typically occurs gradually over several months rather than all at once. Mounjaro remains in your system for approximately 4–5 weeks after your final dose, so appetite suppression gradually diminishes during this time. Most significant regain happens within the first 3–6 months after stopping.
Can my GP help me maintain weight after stopping Mounjaro on the NHS?
Yes. NHS tier 3 weight management services provide ongoing support including behaviour change programmes, dietitian input, and regular monitoring. Discuss a maintenance plan with your prescriber before stopping treatment. Your GP can also refer you to community weight management programmes or digital tools to track progress.
Is it possible to take Mounjaro again if I regain weight after stopping?
Yes, restarting Mounjaro is an option some people pursue, though this depends on NHS availability in your area and your prescriber's assessment. Some weight management services now recommend longer-term or "on-off" treatment cycles rather than one-off courses. Discuss long-term options with your GP before stopping.
What's the difference between stopping Mounjaro and stopping other weight loss injections like Wegovy?
Both Mounjaro (tirzepatide) and Wegovy (semaglutide) cause similar weight regain patterns when stopped—the appetite-suppressing effects wear off and weight typically returns gradually without lifestyle maintenance. Mounjaro's dual GIP/GLP-1 mechanism may produce slightly different individual outcomes, but underlying principles are the same.
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.