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
Not Losing Weight On 2.5 Mounjaro — What's Normal?
If you're not seeing weight loss results on the 2.5 mg starting dose of Mounjaro, you're not alone — and this is often completely normal. The 2.5 mg dose is a titration dose designed to help your body adjust to the medication, not the therapeutic dose. Most people require dose escalation to experience meaningful weight loss. Understanding how Mounjaro works, what to expect at each stage, and your options for accessing this weekly weight loss injection in the UK can help you make informed decisions about 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 2.5 mg Often Doesn't Produce Weight Loss
The 2.5 mg starting dose of Mounjaro is a titration dose — its primary purpose is to allow your body to adjust to the medication and minimise side effects, not to deliver therapeutic weight loss. Clinical evidence shows that meaningful weight loss typically occurs at higher maintenance doses. A prescriber will usually increase your dose every four weeks, moving through 5 mg, 7.5 mg, 10 mg, 12.5 mg, and potentially up to the maximum 15 mg once-weekly dose.
- Weeks 1–4 (2.5 mg): Adjustment phase; some appetite suppression may occur but weight loss is typically minimal
- Weeks 5–8+ (5 mg and above): Therapeutic effects increase; weight loss typically becomes noticeable
- Therapeutic window: Most people see results at 5 mg or higher
It's important to discuss your progress at each dose escalation with your prescriber. They can assess whether you're experiencing expected side effects and whether dose increases are appropriate for you. Our GLP-1 weight loss calculator can help you understand projected outcomes at different doses — though individual results vary significantly.
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: Cost and Routes
There are two main routes to access Mounjaro in the UK: through the NHS or privately. NHS access is through specialist tier 3 or 4 weight management services, typically requiring a GP referral and assessment. Availability varies by region and waiting times can be substantial — some ICBs have waiting lists of 12+ months. Private access is through GPhC-registered online pharmacies following a consultation with a UK-licensed prescriber. Private costs typically range from £129 to £280+ per month depending on dose. A private Mounjaro KwikPen (containing 4 weekly doses) generally costs between £130 and £280. When comparing cost versus outcome, remember that dose titration takes 16+ weeks, so initial costs are typically at lower doses before moving to therapeutic levels.
- 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 it normal to not lose weight on 2.5 mg Mounjaro?
Yes, completely normal. The 2.5 mg dose is a starting/titration dose designed for adjustment, not weight loss. Most people need to reach 5 mg or higher to see meaningful results. This typically takes 4–8 weeks. Always discuss your progress with your prescriber before considering dose changes.
How long should I stay on 2.5 mg before increasing?
The standard protocol is to remain on each dose for a minimum of four weeks before escalation. This allows your body to adjust and your prescriber to assess how you're responding. If side effects are significant, your prescriber may extend this period.
What's the difference between NHS and private Mounjaro in the UK?
Both NHS and private routes offer the same medication. The main difference is access route and cost. NHS is free but involves waiting lists and referral; private costs £129–£280+ per month but is often faster to access through an online consultation with a licensed prescriber.
How much does Mounjaro cost privately in the UK?
Private Mounjaro typically costs £130–£280 per month depending on dose and provider. A full KwikPen (4 weekly injections) costs roughly £130–£280. Starting at 2.5 mg (lower cost) but progressing to higher therapeutic doses will increase your monthly expenditure as you titrate upwards.
Can I track my progress if I'm not losing weight initially?
Yes — use our free BMI calculator to monitor your personal BMI over time, and our progress tracker to log weekly weight changes. These tools help you see patterns beyond day-to-day fluctuation and give your prescriber useful data for dose adjustment decisions.
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.