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
I've Stopped Losing Weight on Mounjaro — What Next?
If you've reached a weight loss plateau on Mounjaro, you're not alone — many people experience slower weight loss after initial results. This can happen for several reasons, and there are evidence-based options available to help restart progress. Understanding what causes plateaus and knowing when to speak with your prescriber about adjusting your dose or exploring alternatives like Wegovy can help you move forward with your weight management journey.
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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.
Why Weight Loss Plateaus Happen on Mounjaro
Weight loss plateaus are a normal part of any weight management journey, and they occur for several biological and practical reasons. As your body adapts to a lower weight, your metabolic rate may decrease slightly, meaning your body burns fewer calories at rest. Your body may also develop increased tolerance to the medication's effects over time, particularly if your dose hasn't been adjusted in several months. Additionally, if your current Mounjaro dose was optimised for an earlier stage of your weight loss, it may no longer be sufficient to support continued progress at your new weight. Other factors include inconsistent calorie deficit, reduced physical activity, or insufficient sleep. Some people find that their eating patterns have gradually changed, or they've unconsciously increased portion sizes as they've become accustomed to the medication's appetite-suppressing effects. It's also worth checking whether you're tracking progress accurately — sometimes a weekly weight loss injection like Mounjaro works best when combined with consistent lifestyle habits rather than relying on medication alone.
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.
Accessing Options: Dose Adjustment and Alternatives
Your prescriber may recommend increasing your Mounjaro KwikPen dose if you're not yet on the maximum 15 mg weekly dose — this is often the first step when weight loss slows. Dose titration should follow the standard 4-week minimum intervals between increases. If you're already on a higher dose or if further increases aren't appropriate for you, exploring alternatives such as Wegovy (semaglutide) may be discussed, as some people respond differently to different weight loss injections. The cost and access route you choose — whether prescription weight loss UK via NHS specialist services or through private online consultation — will determine how quickly you can explore these options. Using our free GLP-1 weight loss calculator can help you understand potential outcomes at different doses before speaking with your prescriber.
- 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.
Can I increase my Mounjaro dose if I've stopped losing weight?
Yes, dose increases are a standard approach when weight loss plateaus occur. Most people on Mounjaro aren't at the maximum 15 mg dose initially. Your prescriber can assess whether a dose increase is appropriate for you — increases must follow the standard 4-week intervals between each step. Discuss your plateau with your prescriber to explore this option.
Is stopping Mounjaro and switching to Wegovy a good idea?
Switching between medications like Mounjaro and Wegovy is possible, though it requires prescriber guidance. Some people respond differently to different weight loss injections — a dual GIP/GLP-1 agonist like Mounjaro versus a GLP-1-only medication like Wegovy may suit different individuals. Never stop or switch medications without medical advice.
How long should I expect weight loss to continue on Mounjaro?
Weight loss typically continues for the first 12–24 months on Mounjaro, though the rate naturally slows after initial loss. Plateaus are normal and don't mean the medication has stopped working. Many people maintain their weight loss long-term with continued use, though some choose to stop after reaching their goal.
What should I discuss with my prescriber about my weight loss plateau?
Discuss: your current dose, how long you've been on it, your current lifestyle habits (diet, activity, sleep), any changes in how you're feeling, and whether you're on any other medications. Your prescriber can then assess whether dose adjustment, lifestyle changes, or exploring alternative medications is appropriate for you.
Where can I get a Mounjaro prescription in the UK if I want to explore options?
Access routes include NHS specialist tier 3 weight management services (via GP referral, though waiting lists vary) or private online consultations with UK-licensed prescribers followed by dispensing through GPhC-registered pharmacies. Private routes are typically faster but involve personal cost. Our BMI calculator can help confirm whether you meet eligibility criteria.
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.