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
Can Milk Thistle Help With Weight Loss?
Milk thistle is a traditional herbal supplement sometimes marketed for liver health and weight management, but evidence for weight loss is limited. If you're looking for effective weight management support in the UK, prescription options like Mounjaro and Wegovy have strong clinical evidence. Both are available through NHS specialist services or private prescribing for eligible adults. This guide explains the difference between herbal supplements and proven weight loss medication, and how to access prescription support if you meet the criteria.
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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.
UK-Licensed Prescription Weight Loss Options
If you're interested in weight management, the UK has three prescription medications with strong clinical evidence: Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide). Unlike herbal supplements such as milk thistle, these are prescription-only medicines that require clinical assessment.
In clinical trials, Mounjaro helped patients lose an average of 15–21% of body weight, while Wegovy supported approximately clinically studied weight loss — though individual results vary significantly. Both work by mimicking natural hormones that regulate appetite and blood sugar. You may be eligible if you have a BMI of 30 or above, or a BMI of 27–29.9 with weight-related health conditions such as type 2 diabetes, high blood pressure, or sleep apnoea.
Eligibility thresholds are lower for adults of South Asian, Chinese, Black African, or Black Caribbean heritage. Use our free BMI calculator above to check your personal BMI and understand whether you might meet eligibility criteria for prescription weight loss support.
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.
NHS vs Private Access and Next Steps
In the UK, you can access prescription weight loss medication through two routes: NHS specialist weight management services or private prescribing. NHS access requires referral from your GP to a tier 3 or tier 4 specialist service, though availability and waiting times vary significantly by region. Private access is faster — you can have an online clinical assessment and prescription within days — but involves private costs.
Your first step is to have a conversation with your GP about weight management options. They can discuss whether prescription medication might be suitable for you, refer you to NHS services if appropriate, or explain private options. Prescription weight loss medication works best alongside dietary changes and increased physical activity. Our GLP-1 weight loss calculator can help you estimate potential results at different doses if you decide to explore this route further.
- 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 milk thistle proven for weight loss?
No. Milk thistle is traditionally used for liver health, but there is no strong clinical evidence that it helps with weight loss. Studies are limited and results are inconclusive. If you're seeking effective weight loss support, prescription medications like Mounjaro and Wegovy have robust clinical trial data showing meaningful results for eligible adults.
What prescription weight loss medicines are available in the UK?
Three prescription options are licensed in the UK: Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide). All are once- or twice-weekly injections. Mounjaro and Wegovy are once-weekly; Saxenda is once-daily. Each requires a clinical assessment before prescription, and all work best alongside lifestyle changes.
Who is eligible for prescription weight loss medication in the UK?
Generally, you may be eligible if you have a BMI of 30 or above, or 27–29.9 with weight-related conditions like type 2 diabetes, high blood pressure, or sleep apnoea. Eligibility thresholds are lower (BMI 27.5+) for adults of South Asian, Chinese, Black African, or Black Caribbean heritage. Your GP or a licensed prescriber can assess your individual eligibility.
Can I get weight loss medication on the NHS?
Yes, prescription weight loss medication is available through NHS specialist weight management services. You'll need a referral from your GP to a tier 3 or tier 4 service. Availability and waiting times vary by region, and NHS services typically manage your care through a multidisciplinary team. Private prescribing is also available for eligible adults.
How much weight can I expect to lose with prescription medication?
Clinical trial results show Mounjaro helped patients lose 15–21% of body weight on average, and Wegovy supported approximately 15% loss. However, individual results vary significantly based on factors like diet, exercise, dose, and metabolism. Results are achieved alongside a reduced-calorie diet and increased physical activity — medication alone is not a solution.
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.