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
Dramatic Weight Loss Programs in the UK: Prescription Options Explained
If you're considering a dramatic weight loss program in the UK, prescription medications may be part of your journey. The NHS and private services now offer several clinically-proven weight management options, including GLP-1 and dual-action injections. These are prescription-only medicines that work alongside lifestyle changes. This guide explains what's available, who is eligible, and how to access support through both NHS and private routes. Always consult your GP to discuss whether prescription weight loss medication is appropriate for your individual circumstances.
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 Prescription Weight Loss Medications
Three prescription medications are currently licensed in the UK for weight management: Mounjaro (tirzepatide), a dual GIP and GLP-1 receptor agonist; Wegovy (semaglutide), a GLP-1 receptor agonist; and Saxenda (liraglutide), also a GLP-1 agonist given as a daily injection rather than weekly. In clinical trials, adults using these medications achieved an average weight loss of 14–21% of their body weight when combined with a reduced-calorie diet and increased physical activity—results vary significantly between individuals.
Eligibility for prescription weight loss medication typically requires a BMI of 30 or above, or a BMI of 27–29.9 with at least one weight-related health condition such as type 2 diabetes, high blood pressure, or heart disease. For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower BMI thresholds due to higher health risks at lower weights. All prescription weight loss medications are subject to clinical assessment before being prescribed, and they work best as part of a comprehensive weight management uk approach combining dietary changes and physical activity. Use our GLP-1 weight loss calculator to estimate potential outcomes, and our BMI calculator to understand your current health status.
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.
Accessing Prescription Weight Loss: NHS vs Private Routes
In England and Wales, NHS access to prescription weight loss medication is through specialised tier 3 and tier 4 weight management services. Your GP can refer you to these services, though waiting times and availability vary significantly by region. The NHS weight loss pathway prioritises evidence-based support, but demand often exceeds capacity, meaning waiting lists can extend several months or longer in some areas.
Privately, prescription weight loss medications are available through GPhC-registered online services following a clinical assessment with a UK-licensed prescriber. Private prescriptions typically take days to process, though costs range from approximately £129–£320 per month depending on the medication and dose. Whether you choose NHS or private routes, a qualified healthcare professional must assess your suitability based on your medical history, current medications, and weight management goals. Speak with your GP first to explore all available options and determine the best route for your dramatic weight loss program needs.
- 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.
What is the difference between Mounjaro and Wegovy for weight loss?
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist, while Wegovy (semaglutide) is a single GLP-1 agonist. In clinical trials, Mounjaro users lost an average of 15–21% of body weight, compared to approximately 15% for Wegovy users. Individual results vary, and the choice between them depends on clinical assessment by your prescriber and your personal health profile.
Am I eligible for prescription weight loss medication on the NHS?
NHS eligibility typically requires a BMI of 30 or above, or 27–29.9 with weight-related health conditions like diabetes or high blood pressure. Adults of South Asian, Chinese, Black African, or Black Caribbean heritage may qualify at lower BMI levels. Your GP can assess your eligibility and refer you to specialist weight management services, though regional availability varies.
How quickly can I get prescription weight loss medication privately in the UK?
Private prescription weight loss medications are typically available within days of a successful online clinical assessment. You'll need to complete a consultation with a UK-licensed prescriber, who will assess your suitability. Costs vary by medication and dose, ranging from approximately £129–£320 monthly. Always ensure the provider is GPhC-registered.
Will prescription weight loss medication alone result in dramatic weight loss?
No. Prescription medications such as Mounjaro and Wegovy work best alongside a reduced-calorie diet and increased physical activity. Clinical trial data shows these medications help users achieve an average of 14–clinically studied weight loss when combined with lifestyle changes. Your prescriber will discuss realistic expectations and the importance of ongoing behaviour modification for sustained results.
Can I switch between Mounjaro and Wegovy once I've started?
Switching between medications should only be done under the guidance of your prescriber. While both are GLP-1-based (Mounjaro is dual-action), they have different dosing schedules and mechanisms. Any medication change requires clinical assessment to ensure it remains appropriate for your health and weight management goals. Never stop or switch medications without professional guidance.
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.