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
Why Does Weight Loss Stall on Mounjaro?
Weight loss plateaus on Mounjaro are common and usually temporary. A stall—where weight remains stable for several weeks—can happen for several reasons: your body adapting to the medication, insufficient calorie deficit, reduced adherence to diet changes, or simply reaching a new baseline before further loss occurs. Understanding why this happens and how to access Mounjaro in the UK can help you manage expectations and explore your options. Whether you're considering NHS or private prescription routes, costs vary significantly depending on your chosen pathway.
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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.
Common Reasons for Mounjaro Weight Loss Plateaus
A weight loss stall on Mounjaro typically reflects normal physiology rather than medication failure. As you lose weight, your metabolic rate decreases, meaning your body requires fewer calories at a lower weight. Additionally, dose tolerance can develop—your appetite-suppressing response may gradually reduce if you remain on the same dose for an extended period. This is why Mounjaro supports dose titration, with increases every 4 weeks up to the maximum 15 mg. Insufficient calorie deficit is another factor: even with reduced appetite, you must maintain a meaningful calorie reduction for continued loss. Environmental factors like increased stress, poor sleep, or reduced physical activity can stall progress. Finally, as you approach your goal weight, loss naturally slows. Clinical trials show that most weight loss occurs in the first 12–16 weeks; subsequent progress may be slower but achievable with consistent effort alongside your weekly weight loss injection.
- Metabolic adaptation at lower body weight
- Tolerance to appetite suppression at current dose
- Calorie deficit insufficient for further loss
- Lifestyle factors: stress, sleep, activity level
- Natural slowdown as you approach goal weight
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.
Accessing Mounjaro in the UK: NHS vs Private Routes
In the UK, Mounjaro is available through two main pathways. The NHS route requires referral to a tier 3 specialist weight management service through your GP—access varies by region and waiting times can be lengthy. The private route involves online consultation with a UK-licensed prescriber, with prescription dispensed by a GPhC-registered pharmacy if clinically appropriate. Private Mounjaro costs typically range from £130–£300 per month depending on your dose. A UK prescriber will assess your BMI, health conditions, medications, and suitability before issuing a prescription. Neither route assures prescription—clinical assessment determines eligibility. Most private consultations take 24–48 hours, whereas NHS referrals can involve months of waiting. Use our free GLP-1 weight loss calculator to understand potential outcomes at different doses.
- 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.
Why has my weight stopped changing on Mounjaro?
Weight loss plateaus are normal and usually temporary. Common causes include metabolic adaptation at your lower weight, tolerance to your current dose, insufficient calorie deficit despite reduced appetite, and natural slowdown as you approach your goal. Your prescriber may recommend dose titration, dietary review, or increased physical activity to restart progress.
How much does Mounjaro cost privately in the UK?
Private Mounjaro typically costs £130–£300 per month depending on your dose (2.5 mg to 15 mg). Prices vary between GPhC-registered pharmacies. The 2.5 mg starting dose is usually cheaper than higher maintenance doses. Always confirm the total cost including the consultation fee before proceeding.
Can I get Mounjaro on the NHS for weight loss?
Yes, Mounjaro is NICE-approved for NHS weight management services. However, access is through specialist tier 3 services, not routine GP prescription. You must be referred by your GP and meet BMI thresholds (BMI ≥30, or ≥27.5 with weight-related health conditions). Regional availability and waiting times vary significantly.
What does an online Mounjaro consultation involve?
A UK-licensed prescriber will review your medical history, current medications, BMI, and health conditions via an online questionnaire or video call. They'll assess your suitability for Mounjaro based on UK eligibility criteria. If approved, a prescription is issued and dispensed by a GPhC-registered pharmacy. The process typically takes 24–48 hours.
Is Mounjaro the same as Wegovy for weight loss?
Both are prescription-only weekly injections, but they're different medications. Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist; Wegovy (semaglutide) activates GLP-1 only. Clinical trials show slightly higher average weight loss with Mounjaro (~21% body weight vs ~15% with Wegovy), though individual results vary. Both require clinical assessment before prescription.
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.