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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Weight Loss Stall on Mounjaro: Causes and Solutions
If you're taking Mounjaro and your weight loss has slowed or stopped, you're not alone. A weight loss stall — sometimes called a plateau — is common on weekly weight loss injections and doesn't necessarily mean the medication isn't working. Understanding why it happens and what options are available can help you and your prescriber decide on next steps. This guide explains the causes, what you can do about it, and how to access support through both NHS and private routes in the UK.
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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.
Why Weight Loss Plateaus Happen on Mounjaro
A weight loss plateau on Mounjaro typically occurs after 3–6 months as your body adapts to the medication. Several factors contribute to this:
- Metabolic adaptation: As you lose weight, your body adjusts its energy needs downward, reducing the calorie deficit naturally created by the medication.
- Dose stabilisation: If you're on a stable dose, your body gradually becomes accustomed to the appetite-suppressing effects, which can diminish over time.
- Lifestyle plateau: If dietary or physical activity changes have stalled, weight loss may pause despite the medication continuing to work.
- Individual variation: GLP-1 medications like this weekly weight loss injection affect everyone differently — some people see continued loss, others plateau earlier.
A plateau doesn't mean Mounjaro has stopped working. Clinical data shows that sustained weight loss is maintained even during plateaus. Your GP or prescriber can assess your individual situation and discuss whether dose adjustment, known as dose titration, might help.
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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 Support and Dose Adjustments in the UK
If you're experiencing a weight loss stall, your prescriber can review your current dose of the KwikPen and discuss adjustment options. This might involve staying at your current dose longer, increasing to the next step, or reviewing your diet and physical activity with a healthcare professional.
NHS route: You'll be managed through your specialist weight management service, where your prescriber can assess your progress and adjust your prescription weight loss strategy.
Private route: Online consultations allow you to discuss your plateau with a UK-licensed prescriber, who can advise on next steps without NHS referral waiting times. Many private providers offer follow-up consultations specifically for dose reviews and progress discussion.
Our GLP-1 weight loss calculator can help you understand projected outcomes at different doses, and our progress tracker lets you log weekly weight changes to spot patterns your prescriber might find useful.
- 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.
Is a weight loss stall on Mounjaro normal?
Yes, weight loss plateaus are common on GLP-1 medications and don't indicate failure. Your body adapts to the medication over time, which is a normal physiological response. Many people experience plateaus but maintain their weight loss. Your prescriber can review your individual progress and discuss whether any adjustments might help restart loss.
Can my dose be increased if I've hit a plateau?
Possibly. If you're not on the maximum dose of 15mg weekly, your prescriber may discuss increasing to the next dose step. However, dose increases aren't automatically recommended for everyone — your prescriber will consider your current dose, how long you've been stable, and your overall health before suggesting adjustment.
How long do weight loss plateaus typically last?
Plateaus vary significantly between individuals. Some people see renewed weight loss after a few weeks of stable weight; others maintain their plateau long-term. Continuing the medication alongside consistent lifestyle changes offers the best chance of eventual resumed loss. Your prescriber can advise based on your specific situation.
Should I change my diet if weight loss stalls?
Yes. A plateau often signals that your calorie intake and expenditure have balanced out. Working with a dietitian or your GP to review your eating patterns, portion sizes, and physical activity can help restart a deficit. GLP-1 medication works best alongside reduced-calorie diet and increased activity — not instead of them.
Can I access Mounjaro through the NHS if I have a stall?
If you're already on Mounjaro through an NHS specialist weight management service, your plateau will be managed within that service — you don't need a new referral. If you're not yet on the NHS, access typically requires referral from your GP to tier 3 specialist services, though waiting lists vary by region. Private prescription is available without NHS referral.
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.