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
What Does Mounjaro Do For Diabetes?
Mounjaro (tirzepatide) is a prescription-only injection that works differently than traditional diabetes medications. Originally developed for type 2 diabetes management, Mounjaro activates two natural hormone pathways — GIP and GLP-1 — helping regulate blood sugar levels. In the UK, it's approved for both diabetes and weight management, particularly for adults with type 2 diabetes who struggle with blood sugar control or weight. Understanding how Mounjaro works, what it costs, and how to access it through NHS or private routes can help you discuss this option with your GP.
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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.
How Mounjaro Works For Type 2 Diabetes
Mounjaro's dual mechanism is what sets it apart. As a GIP and GLP-1 receptor agonist, it mimics natural hormones your body produces after eating. It stimulates the pancreas to release insulin in response to food, slows how quickly food leaves your stomach, and helps your liver produce less glucose when blood sugar is already controlled. This three-way action helps lower HbA1c (your average blood sugar over three months) more effectively than single-action medications.
- Improves insulin secretion in response to meals
- Reduces liver glucose production
- Slows gastric emptying (food moves through your stomach more slowly)
- Supports weight loss, which also improves blood sugar control
Clinical trials show that Mounjaro can lower HbA1c by an average of 2–2.5 percentage points, depending on the dose used. Individual results vary, and effectiveness depends on lifestyle factors including diet and physical activity.
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.
Mounjaro Cost And Access In The UK
NHS access to Mounjaro for diabetes is available but varies by region. Your GP can refer you to a specialist diabetes service if Mounjaro is appropriate for your case. However, NHS prescribing for type 2 diabetes typically follows NICE guidelines, which recommend trying other medications first. Waiting lists for NHS specialist services can be lengthy in many areas.
Private prescription routes are faster. Private GPs and online clinics can prescribe Mounjaro following a clinical assessment. Private costs typically range from £150–£300 monthly depending on your dose. The Mounjaro KwikPen contains four weeks of doses. You'll also need regular blood tests to monitor your HbA1c and kidney function — these may incur additional costs through private providers.
- 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 Mounjaro only for weight loss, or does it treat diabetes?
Mounjaro (tirzepatide) was originally developed for type 2 diabetes. It's licensed in the UK for both diabetes management and weight loss. For diabetes, it helps lower blood sugar by improving insulin secretion and reducing liver glucose production. Many people experience weight loss as a secondary benefit, which further improves blood sugar control.
How long does it take to see results with Mounjaro for diabetes?
Most people see improvements in blood sugar control within 2–4 weeks, though the full effect develops over 8–12 weeks as your dose increases. HbA1c reductions (your three-month average) are typically measured after 12 weeks on a stable dose. Individual response varies based on starting HbA1c, diet, and activity levels.
Can I get Mounjaro on the NHS for type 2 diabetes?
Yes, Mounjaro is available through NHS specialist diabetes services, but access depends on your local ICB (Integrated Care Board) and NICE guidance. Your GP can refer you if other medications haven't worked adequately. NHS prescribing typically follows a stepwise approach, so you may need to try other medications first. Waiting times vary significantly by region.
What's the difference between Mounjaro and Ozempic for diabetes?
Both contain semaglutide for Ozempic and tirzepatide for Mounjaro, but they work slightly differently. Mounjaro is a dual GIP and GLP-1 agonist (two mechanisms), while Ozempic is GLP-1 only. For type 2 diabetes, Mounjaro often shows greater HbA1c reduction in clinical trials. The choice depends on individual factors your specialist will assess.
Do I need blood tests while taking Mounjaro?
Yes. Your GP or prescriber will monitor your HbA1c (blood sugar control) typically every 3 months, and your kidney function (eGFR) periodically. If you have a history of thyroid problems, thyroid markers may also be checked. Regular monitoring ensures the medication is working and safe for you. NHS monitoring is included in your care; private providers may charge for blood tests.
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.