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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Can You Take Mounjaro With Fatty Liver?
If you have been diagnosed with non-alcoholic fatty liver disease (NAFLD) and are considering Mounjaro for weight management, it's important to understand how this medication interacts with liver health. Mounjaro (tirzepatide) is a prescription-only GLP-1 receptor agonist that may help with weight loss, but individuals with fatty liver disease require specific medical assessment before starting treatment. Your GP or a licensed prescriber will evaluate your liver function and overall health before deciding whether Mounjaro is suitable for you. This guide explains what you need to know about using Mounjaro with fatty liver, how to access it in the UK, and what the process involves.
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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.
Mounjaro and Fatty Liver Disease — What the Evidence Shows
Non-alcoholic fatty liver disease (NAFLD) is present in around 20–30% of UK adults, often linked to excess weight and metabolic conditions. When considering prescription weight loss medication like Mounjaro, liver function becomes a key safety consideration.
Mounjaro may benefit people with fatty liver disease because:
- Weight loss of 5–10% can significantly improve fatty liver progression
- Clinical trials showed Mounjaro helps participants lose an average of 15–21% of body weight when combined with dietary changes and increased physical activity
- Improved weight may help reduce liver fat accumulation and inflammation
However, Mounjaro requires careful assessment before starting. Your prescriber will typically check your liver function tests (LFTs) including ALT, AST, and bilirubin levels before prescribing tirzepatide. Some people with severe liver disease or cirrhosis may not be suitable candidates. The dose titration schedule — where you start at 2.5 mg and gradually increase to a maintenance dose — allows your body to adjust while liver function is monitored. Always inform your prescriber if you have a history of liver disease, as this affects eligibility and dosing decisions.
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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.
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Accessing Mounjaro in the UK — NHS vs Private Routes and Costs
In the UK, you can access Mounjaro through two routes: NHS specialist services or private prescription. NHS access is limited and typically requires referral to a tier 3 or tier 4 specialist weight management service. Waiting lists vary significantly by region and can extend several months or longer in many areas.
Private route: Private prescribers can assess your suitability and issue a prescription if clinically appropriate. Online consultations are available from GPhC-registered prescribers, with costs typically ranging from £129–£320 per month depending on your dose and provider. Each KwikPen contains a 4-week supply of one dose. To access private prescription weight loss treatment, you'll have an online consultation, provide your medical history, and the prescriber will assess whether Mounjaro (or an alternative like Wegovy) is suitable. If approved, the prescription is sent to a registered pharmacy for dispensing. Always check that the prescriber is UK-licensed and the pharmacy is GPhC-registered.
- 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 safe if I have fatty liver disease?
Mounjaro may help people with fatty liver disease lose weight, which can improve liver health. However, you require a clinical assessment first. Your prescriber will check your liver function tests and medical history. People with severe liver disease or cirrhosis may not be suitable. Always disclose your fatty liver diagnosis when seeking a prescription.
How much does Mounjaro cost privately in the UK?
Private Mounjaro costs typically range from £129–£320 per month depending on your dose. Starting doses (2.5 mg) are usually cheaper than maximum doses (15 mg). Each KwikPen provides 4 weeks of injections. Prices vary by provider, so it's worth checking different GPhC-registered pharmacies for the best value.
Can I get Mounjaro on the NHS if I have fatty liver disease?
NHS access to Mounjaro is through specialist weight management services, typically tier 3 or tier 4. You'll need a referral from your GP and must meet BMI and eligibility criteria. Fatty liver disease may support your case for referral, but availability varies significantly by region. Ask your GP about waiting lists in your area.
What's the difference between Mounjaro and Wegovy for fatty liver?
Both are GLP-1-based weight loss medications, but Mounjaro (tirzepatide) is a dual GIP and GLP-1 agonist, while Wegovy (semaglutide) is a GLP-1 agonist only. Clinical trials suggest Mounjaro may offer slightly higher average weight loss. Both require clinical assessment. Your prescriber will recommend the most suitable option based on your health profile.
What happens at an online consultation for Mounjaro?
A UK-licensed prescriber will review your medical history, current medications, and health conditions including your fatty liver diagnosis. They'll discuss your weight loss goals and any previous treatments. If suitable, they'll issue a prescription sent to a registered pharmacy. The entire process typically takes a few days. Always use a prescriber registered with the GMC or RCGP.
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