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
Maintaining Weight Loss After Mounjaro: Mounjaro vs Wegovy
Stopping a weekly weight loss injection like Mounjaro raises an important question: how do you maintain the weight loss you've achieved? Both Mounjaro (tirzepatide) and Wegovy (semaglutide) can support significant weight reduction when used alongside lifestyle changes, but long-term success depends on sustained diet and physical activity habits. This guide compares how these two prescription weight loss medications work, their clinical trial outcomes, and what the evidence shows about maintaining results after treatment. Understanding the differences helps you and your GP make informed decisions about which option suits your individual health needs.
10,000+ calculations today · NHS-aligned thresholds · 100% free
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.
Mounjaro vs Wegovy: Clinical Trial Data and Maintenance
Both Mounjaro and Wegovy are GLP-1 receptor agonist medications approved in the UK for weight management, but they work through different mechanisms. Mounjaro (tirzepatide) is a dual GIP and GLP-1 agonist, activating two hormone pathways simultaneously, while Wegovy (semaglutide) is a GLP-1 agonist only. In clinical trials, the SURMOUNT-1 study showed Mounjaro helped participants lose approximately 20.9% of body weight at the maximum dose (15 mg weekly) over 72 weeks. The STEP-1 trial for Wegovy showed average weight loss of around 14.9% body weight at 2.4 mg weekly over 68 weeks. Both trials combined medication with reduced-calorie diet and increased physical activity—results varied significantly between individuals. For maintaining weight loss after stopping either medication, the critical factor is that the lifestyle changes (diet and exercise) must continue independently of the injection itself.
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.
Long-Term Weight Maintenance: Prescriber Guidance and Individual Suitability
Neither Mounjaro nor Wegovy is designed as a short-term intervention—both are typically used as ongoing treatments, with prescribers monitoring your progress and adjusting doses as needed. Some people benefit from continuing medication long-term, whilst others may pause or stop if they achieve stable weight management through diet and exercise alone. Your GP or prescriber will assess whether continuing, pausing, or switching medications suits your individual circumstances. Key to maintenance is tracking progress using structured methods—our free progress tracker helps you log weight, diet, and exercise consistently. Both medications can be used alongside NHS healthy weight guidance, which emphasises sustainable calorie deficit (around 500 kcal/day for 0.5 kg weekly loss), increased physical activity, and behaviour change. Whichever medication you've used, long-term success depends on the habits you've built during treatment, not the injection alone.
- 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 regain weight after stopping Mounjaro?
Many people regain some weight after stopping Mounjaro if diet and exercise habits revert to pre-treatment levels. Clinical evidence shows that sustained lifestyle changes are essential for maintaining loss long-term. Your prescriber can advise whether continuing, pausing, or switching to Wegovy might support your individual goals.
Which is better for long-term weight maintenance: Mounjaro or Wegovy?
Both can support long-term weight management when combined with sustained lifestyle changes. Mounjaro showed slightly higher average weight loss in trials (20.9% vs 14.9%), but individual results vary significantly. Suitability depends on your health profile, tolerance, and prescriber assessment—neither is universally "better" for maintenance.
Can I switch from Mounjaro to Wegovy to maintain weight loss?
Switching between medications is possible and may be appropriate in some cases, but only under prescriber guidance. There is no standard conversion between doses—your prescriber will assess whether a switch suits your individual needs and restart dosing appropriately.
What happens to appetite after stopping Mounjaro?
Appetite typically increases within days to weeks after stopping Mounjaro as the medication leaves your system. This is why maintaining the healthy eating habits and physical activity you've developed during treatment is crucial. Your GP can advise on behaviour change support if needed.
How can I maintain weight loss using tools and tracking?
Our free progress tracker allows you to log weight, meals, and exercise consistently—this structured approach supports long-term maintenance. Our BMI calculator and weight converter help you monitor progress in UK measurements (stone and pounds) and assess whether you're staying within a healthy range for your height.
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.