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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Not Losing Weight on 5mg Mounjaro โ What You Need to Know
If you've been taking Mounjaro 5mg and haven't seen weight loss yet, you're not alone โ and there are several reasons why this might be happening. In clinical trials, most participants required dose escalation beyond 5mg to achieve meaningful weight loss. This guide explains what's normal, when to expect results, and how to access treatment options in the UK through both NHS and private routes.
10,000+ calculations today ยท NHS-aligned thresholds ยท 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/mยฒ).
While BMI isn't a perfect measure โ it doesn't account for muscle mass, bone density, or fat distribution โ 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 โ 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 5mg Mounjaro May Not Be Producing Weight Loss
Mounjaro 5mg is typically a starting or early adjustment dose, not a therapeutic maintenance dose for most people. Clinical trials show that meaningful weight loss usually begins at higher doses โ particularly 10mg and 15mg. Several factors may explain why you're not seeing results at 5mg:
- Dose timing: You may simply not have been on 5mg for long enough. The medication requires at least 4 weeks at each dose level before titrating upwards, so you need a minimum of 8โ12 weeks total before expecting significant weight loss.
- Lifestyle factors: Mounjaro works alongside a reduced-calorie diet and increased physical activity. Without these changes, weight loss is unlikely regardless of dose.
- Individual variation: Some people require higher doses to experience appetite suppression and the full GLP-1 effect.
- Medical conditions: Certain conditions (thyroid disorders, PCOS, certain medications) can affect weight loss response.
The dose escalation process is designed to find the right level for your body. Your prescriber will typically increase you to 7.5mg at week 9, then 10mg at week 13 if tolerated โ where most people begin to see noticeable results.
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 โ 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 โ completely free.
Accessing Mounjaro in the UK โ Cost and Route Options
In the UK, you can access Mounjaro through NHS specialist services or private online prescribing. Cost and timeline differ significantly between routes:
- NHS route: Prescription is free at point of use, but access is through tier 3 specialist weight management services. Waiting times vary by region (often several months to over a year). You'll need a GP referral and clinical assessment at a specialist centre.
- Private route: Available through UK-licensed prescribers via online consultation. Costs range from approximately ยฃ129โยฃ180 per month for 5mg doses, rising to ยฃ250โยฃ320 for higher doses (10โ15mg). Treatment begins within days rather than months. A clinical assessment is still required before prescription.
Track your progress with our free GLP-1 weight loss calculator to project potential outcomes at different doses, and use our BMI calculator to monitor changes as you escalate.
- 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 โ 5mg โ 7.5mg โ 10mg โ 12.5mg โ 15mg
- GLP-1 receptor agonist
- Up to 15โ17% body weight loss (STEP trials)
- Weekly injection, 5-step dose escalation
- NHS & private prescription available
- Doses: 0.25mg โ 0.5mg โ 1mg โ 1.7mg โ 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 | 15โ22.5% | 12โ17% |
| Key trial | SURMOUNT-1 (2022) | STEP 1 (2021) |
| Max dose | 15 mg weekly | 2.4 mg weekly |
| Escalation period | 20โ32 weeks | 16โ20 weeks |
| Administration | Weekly injection (pen) | Weekly injection (pen) |
| NHS availability | Private prescription only | NHS & private |
| Approx. private cost | ยฃ150โยฃ250/month | ยฃ150โยฃ300/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 โ 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.
Should I stay on 5mg Mounjaro or ask for a dose increase?
If you've been on 5mg for 4+ weeks and tolerating it well, the standard protocol is dose escalation. Discuss with your prescriber about moving to 7.5mg or 10mg. Most weight loss occurs at higher doses in clinical trials. Individual tolerance and any side effects also factor into your prescriber's recommendation.
How long does it take to see weight loss results on Mounjaro?
Most people see noticeable weight loss between weeks 9โ16 once they reach a therapeutic dose (typically 10mg or above). At 5mg, you may see modest changes, but significant loss is rare. Combined with a calorie deficit and exercise, results become more apparent at higher doses.
What's the difference between Mounjaro and Wegovy for weight loss?
Both are prescription weight loss injections. Mounjaro (tirzepatide) is a dual GIP/GLP-1 agonist; Wegovy (semaglutide) is a GLP-1-only agonist. Clinical trials show similar weight loss averages (~15โ21% for Mounjaro, ~15% for Wegovy). Your prescriber will recommend the most suitable option based on your health profile.
Can I access Mounjaro on the NHS if I'm currently on a private prescription?
Yes, you can switch from private to NHS if referred to a tier 3 specialist weight management service by your GP. However, NHS eligibility and availability vary significantly by region. You'll need to meet local ICB criteria and may face a waiting list. Speak to your GP about NHS referral options in your area.
What happens if I'm not tolerating the side effects at 5mg โ can I stay on this dose long-term?
Staying on 5mg long-term is possible if side effects prevent escalation, but weight loss results will likely remain minimal. Work with your prescriber to manage side effects (nausea, diarrhoea are common initially). Often these improve after 2โ4 weeks. Dose escalation may still be worth trying once you've adapted.
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.