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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Natural Weight Loss Help — UK Prescription Medication Guide
If you're looking for natural weight loss help beyond diet and exercise, prescription weight management medication may be an option worth exploring with your GP. The UK has several licensed medications available that work with your body's natural hunger hormones to support weight management. This guide covers the prescription options available to eligible adults in the UK, how they work, and how to find out if you might be suitable for treatment. Understanding all your weight management options—including medication—is an important step toward finding an approach that works for you.
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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.
UK-Licensed Prescription Weight Loss Medications
Three main prescription medications are licensed in the UK for weight management and are available through both NHS specialist services and private prescribers following clinical assessment:
- Mounjaro (tirzepatide) — A once-weekly injection that works as a dual GIP and GLP-1 receptor agonist, helping regulate appetite and food cravings. Clinical trials showed adults lost an average of 15–21% of their body weight when using Mounjaro alongside diet and exercise changes.
- Wegovy (semaglutide) — A once-weekly GLP-1 receptor agonist injection. Evidence from clinical trials demonstrated average weight loss of around 15% of body weight at the maximum dose, again combined with lifestyle changes.
- Saxenda (liraglutide) — A once-daily GLP-1 injection, offering an alternative for those who prefer daily dosing. These medications are all prescription-only and require a clinical assessment before being prescribed. Weight management medication works most effectively alongside reduced-calorie diet and increased physical activity—they're a tool to support your efforts, not a replacement for lifestyle changes.
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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 Access vs Private Routes — Finding Your Path
In the UK, NHS weight management support is available through specialist tier 3 and tier 4 services. Your GP can refer you if you meet eligibility criteria, though waiting lists vary significantly by region. Many areas have substantial waiting times, sometimes stretching months to years depending on local provision.
Private prescribing offers faster access through GPhC-registered online pharmacies following a remote clinical assessment. If you're eligible—generally requiring a BMI of 30 or above, or 27 and above with weight-related health conditions such as type 2 diabetes, high blood pressure, or sleep apnoea—a prescriber can assess and issue a prescription. Use our free BMI calculator above to check your current BMI, and consider starting a conversation with your GP about which route might suit you best.
- 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 does "natural" weight loss medication mean?
Prescription weight loss medications work with your body's natural hunger hormones rather than using stimulants. Mounjaro and Wegovy are GLP-1 receptor agonists—they mimic and activate a hormone your gut naturally produces after eating, which signals fullness to your brain. This is different from older weight loss drugs that worked through stimulation.
How do I know if I'm eligible for prescription weight loss medication in the UK?
You may be eligible if you have a BMI of 30 kg/m² or above, or a BMI of 27–29.9 with at least one weight-related health condition (type 2 diabetes, high blood pressure, sleep apnoea, or cardiovascular disease). Lower BMI thresholds apply if you're of South Asian, Chinese, Black African, or Black Caribbean heritage. Try our free BMI calculator above to check your status, then discuss options with your GP.
Can I get weight loss medication on the NHS, or do I have to go private?
Both routes are available in the UK. NHS access is through specialist weight management services via GP referral, though waiting lists vary significantly by region. Private access is available through online prescribers following a clinical assessment. Your GP can advise on local NHS provision, or you can explore private options if you prefer faster access.
What's the difference between these medications and diet supplements?
Prescription weight loss medications are clinically tested and approved by the MHRA, with evidence from large clinical trials supporting their effectiveness. They require a prescription and clinical assessment. Dietary supplements are largely unregulated and lack the same level of clinical evidence. Prescription medications work systematically on hunger hormones, whereas supplements vary widely in ingredients and effectiveness.
Will weight loss medication alone help me lose weight?
No—prescription medications work best alongside diet and lifestyle changes. Clinical trials showed weight loss when medication was combined with a reduced-calorie diet and increased physical activity. Think of medication as a tool that supports your efforts by reducing hunger and cravings, making it easier to stick to healthier eating patterns. Try our GLP-1 weight loss calculator to estimate potential results and our progress tracker to monitor your journey.
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.