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
Cytisine Weight Loss — What UK Adults Need to Know
Cytisine is a plant-based alkaloid that has been used in some countries for smoking cessation, but it is not approved or available in the UK for weight management. If you're looking for prescription weight loss support in the UK, there are several licensed medications available through the NHS or private prescribing. This guide explains the approved options, eligibility criteria, and how to access weight loss medication in the UK.
10,000+ calculations today · NHS-aligned thresholds · 100% free
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 Weight Loss Medications
Several prescription medications are currently licensed in the UK specifically for weight management in eligible adults:
- Mounjaro (tirzepatide) — a dual GIP and GLP-1 receptor agonist injected once weekly, available at doses from 2.5 mg to 15 mg
- Wegovy (semaglutide) — a GLP-1 receptor agonist injected once weekly, maximum dose 2.4 mg
- Saxenda (liraglutide) — a GLP-1 receptor agonist injected daily at doses up to 3 mg
In clinical trials, these medications helped participants lose an average of 15–21% of their body weight when combined with reduced-calorie diet and increased physical activity. Individual results vary significantly. Calculate your personal BMI using our free BMI calculator above to understand your starting point and eligibility.
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.
Eligibility and How to Access Treatment in the UK
You may be eligible for prescription weight loss medication if you have a BMI of 30 kg/m² or above, or a BMI of 27–29.9 kg/m² with at least one weight-related health condition such as type 2 diabetes, high blood pressure, or cardiovascular disease. South Asian, Chinese, Black African, and Black Caribbean adults may be eligible at lower BMI thresholds due to increased health risks at these levels.
NHS access: Referral through your GP to a specialist tier 3 weight management service — availability and waiting times vary by region. Private access: Online consultation with a UK-licensed prescriber and dispensing through a GPhC-registered pharmacy. Your GP can discuss which option is right for you and whether prescription weight loss medication is appropriate for your circumstances.
- 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 cytisine available in the UK for weight loss?
No, cytisine is not licensed or approved in the UK for weight loss. While used in some countries for smoking cessation, it has no established role in UK weight management. If you're interested in prescription weight loss medication, your GP can discuss the licensed options available to you.
What weight loss medications are approved in the UK?
Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide) are all licensed for weight management in UK adults. These are GLP-1 or GIP/GLP-1 receptor agonist injections. All are prescription-only and require clinical assessment before being prescribed.
How much weight can I expect to lose with prescription medication?
Clinical trials show average weight loss of 15–21% of body weight over approximately 68–72 weeks, but individual results vary considerably. Weight loss depends on the medication, dose, adherence, and lifestyle changes including diet and physical activity. Your GP or prescriber can discuss realistic expectations for your situation.
Do I need NHS referral to access weight loss injections in the UK?
Not necessarily. NHS access requires referral to a specialist weight management service, which can involve waiting lists. Private prescribing is available through online consultations without NHS referral, though you'll pay privately. Your GP can advise which route is best for you.
What's the difference between Mounjaro and Wegovy?
Mounjaro is a dual GIP/GLP-1 agonist injected once weekly with a maximum dose of 15 mg. Wegovy is a GLP-1 agonist only, also weekly, with a maximum dose of 2.4 mg. Clinical trial data suggests Mounjaro may produce slightly greater average weight loss, but results vary between individuals. Your prescriber will recommend the most suitable option.
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.