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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Weight Loss Medication for Lupus in the UK
Living with lupus can affect your weight through inflammation, medication side effects, and reduced activity levels. If you're struggling with weight management and have lupus, prescription weight loss medication may be an option worth discussing with your GP. The UK has several evidence-based prescription treatments available for eligible adults. Understanding what's available, how to access it, and whether it's suitable for your situation is an important first step. This guide covers UK-licensed weight management options and the NHS pathway for getting support.
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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 Prescription Weight Loss Options
Three prescription weight management medications are licensed in the UK for adults with a BMI of 30 or above, or 27–29.9 with weight-related health conditions. Mounjaro (tirzepatide) is a once-weekly injection that works as a dual GIP and GLP-1 receptor agonist — clinical trials showed average weight loss of around 15–21% of body weight. Wegovy (semaglutide) is also a once-weekly GLP-1 injection, with clinical evidence suggesting average weight loss of approximately 15% of body weight at the maximum dose. Saxenda (liraglutide) is a daily GLP-1 injection with a lower but still meaningful average weight loss of around 5–10%.
All three are prescription-only medicines requiring a clinical assessment before dispensing. Individual results vary significantly. These medications work alongside, not instead of, reduced-calorie diet and increased physical activity. If you have lupus, your prescriber will assess whether GLP-1 weight loss medication is appropriate for your specific health situation.
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
NHS access is through specialist tier 3 weight management services, typically requiring a GP referral. However, NHS waiting times vary greatly by region — some areas have multi-year waiting lists. Private access is available through online consultations with UK-licensed prescribers, without waiting for NHS referral.
Whatever route you choose, the first step is a conversation with your GP. They can discuss your weight management goals, review your current medications (lupus treatments can interact with weight loss injections), and explain your options. Use our free BMI calculator above to check your current BMI — this helps inform the conversation with your healthcare team. Your GP can then advise on NHS eligibility, potential private options, or other weight management support suitable for your lupus.
- 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 take GLP-1 weight loss medication if I have lupus?
This depends on your individual health situation, current lupus medications, and disease activity. Some people with lupus can safely use GLP-1 medications like Mounjaro or Wegovy, but a prescriber must assess this carefully. GLP-1 medications can slow stomach emptying, which may interact with certain lupus treatments. Always discuss your full medical history with your GP or prescriber before starting any weight loss medication.
Will weight loss medication affect my lupus?
GLP-1 medications don't directly affect lupus or autoimmune disease activity based on current evidence. However, they can cause nausea and reduced appetite, which might affect your ability to take lupus medications consistently or get adequate nutrition. A prescriber experienced in managing both lupus and weight loss medication can help you balance these considerations safely.
How do I find out if I'm eligible for NHS weight loss medication?
Start by discussing weight management with your GP. You'll likely need a BMI of 30 or above (or 27+ with weight-related health conditions) to be considered. Your GP can refer you to a specialist tier 3 weight management service if appropriate. Waiting times vary significantly by region — some NHS services have waiting lists of several months or longer.
What's the difference between Mounjaro, Wegovy, and Saxenda?
All three are GLP-1 or dual-action receptor agonist injections for weight management. Mounjaro (tirzepatide) is a newer dual-action medication with the highest average weight loss in trials (~15–21%). Wegovy (semaglutide) is a once-weekly GLP-1 with strong evidence (~15% average loss). Saxenda (liraglutide) is a daily injection with more modest average loss (~5–10%). A prescriber will recommend based on your health needs and suitability.
Can I use the weight converter and progress tracker to monitor my weight?
Yes — our free weight converter helps you switch between kg, stone, and lbs, and our progress tracker lets you log your weight loss journey over time. These tools are useful whether you're using prescription medication or other weight management approaches. Tracking progress can help you and your GP assess whether treatment is working for you.
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.