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 Quotes and UK Prescription Options
Weight loss quotes can provide daily motivation, but sustainable weight management often requires practical support. If you're looking to lose weight in the UK, prescription medications like Mounjaro and Wegovy are now available for eligible adults alongside lifestyle changes. Understanding your options — whether through NHS services or private prescribing — can help you create a realistic plan. This guide explains prescription weight loss options available in the UK and how to find out if you're eligible.
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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 Weight Loss Medications
Three prescription-only medications are currently licensed in the UK for weight management: Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide). Mounjaro and Wegovy are once-weekly injections; Saxenda is a daily injection. These medications work by activating GLP-1 (and in Mounjaro's case, GIP) hormone pathways, helping reduce appetite and support feeling fuller after meals.
Clinical trials show average weight loss of 15–21% body weight with Mounjaro and approximately 15% with Wegovy over 12–18 months — though individual results vary significantly. These are not quick fixes: they work alongside reduced-calorie diet and increased physical activity. All three are prescription-only medicines requiring clinical assessment before being prescribed.
Eligibility typically requires a BMI of 30 or above, or 27 or above with weight-related health conditions such as type 2 diabetes, high blood pressure, or sleep apnoea. For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, lower BMI thresholds may apply due to higher health risks at lower weights. Use our free GLP-1 weight loss calculator to explore how these medications might support your weight management goals.
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 Access vs Private Prescription Routes
NHS access: Prescription weight loss medications are available through NHS specialist weight management services (tier 3/4), typically accessed via GP referral. However, NHS availability varies significantly by region, and waiting lists can be several months to over a year in many areas.
Private access: Private prescribing through UK-licensed online prescribers offers faster access without NHS referral. A licensed prescriber assesses your suitability via online consultation, and if appropriate, issues a prescription dispensed by a regulated pharmacy. Costs range from approximately £129–£320 monthly depending on dose.
Either route requires a genuine clinical assessment — there is no shortcut. Start by speaking to your GP about weight management options. They can discuss both NHS referral and private alternatives, or help you calculate your BMI and health context using our free BMI calculator and weight converter. Being informed helps you make the right choice 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.
What does weight loss medication actually do?
GLP-1 medications like Wegovy mimic natural hormones that signal fullness to your brain, reduce hunger hormones, and slow how quickly food leaves your stomach. They support feeling satisfied on smaller portions. Mounjaro adds a second hormone pathway (GIP) for potentially greater effect. All work alongside diet and activity — they're not replacements for lifestyle change.
Am I eligible for prescription weight loss medication in the UK?
You may be eligible if you have a BMI of 30 or above, or 27 or above with weight-related health conditions (type 2 diabetes, hypertension, sleep apnoea). South Asian, Chinese, Black African, and Black Caribbean adults may be eligible from lower BMI thresholds. Your GP or a licensed prescriber will assess your individual suitability.
How long does it take to see weight loss results?
Weight loss typically begins within 2–4 weeks. Most significant losses occur between weeks 8–16 as your body adjusts to the medication and your appetite reduces. Clinical trials measured results over 12–18 months. Combining medication with reduced calorie intake and increased activity produces better outcomes than medication alone.
What's the difference between Mounjaro and Wegovy?
Mounjaro (tirzepatide) is a dual GIP and GLP-1 agonist; Wegovy (semaglutide) activates GLP-1 only. Clinical trials suggest Mounjaro may produce slightly greater weight loss (up to 21% vs 15%), but both are effective. Individual response varies. Your prescriber will help choose what's suitable for you.
Can I stop taking weight loss medication once I reach my target weight?
Weight loss medications are typically long-term treatments. Stopping medication often leads to weight regain over months, as natural appetite hormones return. Some people use medication maintenance to sustain results; others transition to lifestyle management. Discuss an individual plan with your prescriber rather than stopping suddenly.
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.