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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Mounjaro for PCOS: Before and After — What the Evidence Shows
Mounjaro (tirzepatide) is increasingly prescribed in the UK for weight management in people with polycystic ovary syndrome (PCOS), a condition that often makes weight loss more challenging. This guide explains what Mounjaro can realistically do, how NHS access works, and what to expect when starting this prescription medication. Results vary significantly between individuals, and Mounjaro works best alongside lifestyle changes.
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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 PCOS and Weight Management
PCOS makes weight loss difficult because it affects insulin regulation and hormone balance. Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist — a once-weekly injection that works differently from other medications. It activates two natural hormone pathways that help regulate appetite, reduce food cravings, and support feeling fuller after meals.
- The GLP-1 pathway signals fullness to the brain
- The GIP pathway helps regulate how your body uses glucose and fat
- Combined effect may be particularly helpful for PCOS-related weight management
- Mounjaro requires a prescription and clinical assessment before starting
In clinical trials, people taking Mounjaro at the highest dose (15 mg) lost an average of around 21% of their body weight over 72 weeks — alongside a reduced-calorie diet and increased physical activity. However, individual results vary significantly. Some people see modest changes, whilst others see more substantial weight loss. Your personal response depends on your metabolism, how well you tolerate the medication, your adherence to lifestyle changes, and other individual factors. Use our free GLP-1 weight loss calculator to estimate potential outcomes at different doses based on published trial data.
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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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NHS Eligibility and Access for Mounjaro in PCOS
In the UK, Mounjaro is available through NHS tier 3 specialist weight management services. You typically need a referral from your GP to access these services. Eligibility criteria include a BMI of 30 or above, or 27–29.9 with weight-related health conditions — and PCOS with metabolic complications often qualifies. However, NHS availability varies significantly by region. Some areas have waiting lists of several months or longer.
If NHS waiting times are too long, Mounjaro is also available privately through UK-licensed online prescribers. This route is faster but involves cost (typically £129–£320+ per month depending on dose). Either way, you'll need a clinical assessment to confirm the medication is suitable. Track your progress with our free progress tracker once you start treatment, and use our BMI calculator and weight converter to monitor your metrics in stone and kg.
- 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.
Can I access Mounjaro through the NHS for PCOS in the UK?
Yes, Mounjaro is available through NHS tier 3 specialist weight management services if you meet eligibility criteria (BMI 30+, or 27+ with weight-related conditions). PCOS with metabolic complications often qualifies. You'll need a GP referral. Availability and waiting times vary significantly by region — contact your local integrated care board for details.
What is a realistic weight loss expectation with Mounjaro for PCOS?
Clinical trials showed average weight loss of 15–21% of body weight over 72 weeks at higher doses, alongside diet and exercise. Individual results vary significantly — some see modest changes, others see substantial loss. PCOS doesn't prevent weight loss with Mounjaro, but results depend on your personal response, lifestyle adherence, and individual metabolism.
Is Mounjaro the same as Wegovy for PCOS?
No. Mounjaro (tirzepatide) is a dual GIP+GLP-1 agonist, whilst Wegovy (semaglutide) is a GLP-1 agonist only. Clinical data suggests Mounjaro may produce slightly greater average weight loss, but both are licensed for weight management in the UK. Your GP or prescriber will recommend which is more appropriate for you.
How long does it take to see results with Mounjaro for PCOS?
Weight loss typically becomes noticeable within 4–8 weeks, with more significant changes by 12–16 weeks. Mounjaro requires dose escalation over several weeks (starting at 2.5 mg, increasing by 2.5 mg every 4 weeks up to 15 mg), so full effects take time. Patience and consistent lifestyle changes are essential.
Does Mounjaro affect PCOS hormones directly?
Mounjaro doesn't directly treat PCOS hormones, but weight loss itself often improves insulin resistance and can help restore hormonal balance in PCOS. Many people with PCOS report improved menstrual regularity and reduced symptoms as they lose weight. Discuss how this medication fits with your PCOS management plan with your GP or endocrinologist.
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.