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 Without Workouts: UK Medication Options
Many people ask whether it's possible to lose weight without exercise, and the answer is yes — though combining weight loss approaches tends to work best. In the UK, prescription weight management medications are available for eligible adults, offering a medical approach to weight loss alongside lifestyle changes. These medications work by reducing appetite and helping you feel fuller, making it easier to maintain a calorie deficit. Understanding what's available, who qualifies, and how to access support is the first step toward sustainable weight loss.
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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 Weight Loss Medications
Three prescription medications are currently licensed in the UK for weight management in adults: Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide). These are GLP-1 and GIP/GLP-1 receptor agonist medications that work by reducing hunger signals and supporting appetite control.
Mounjaro is a once-weekly injection with doses ranging from 2.5 mg to 15 mg. In clinical trials, participants lost an average of 15–21% of their body weight — though individual results vary significantly.
Wegovy is also a once-weekly injection (up to 2.4 mg) and showed average weight loss of around 15% in clinical trials. Saxenda is a daily injection (up to 3 mg) with similar effectiveness. All three require a prescription and are not available without a clinical assessment. Use our GLP-1 weight loss calculator to explore potential outcomes at different doses, and check your BMI using our free BMI calculator to understand your starting point.
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 or above, or 27 or above with a weight-related health condition such as type 2 diabetes, high blood pressure, or sleep apnoea. For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, lower thresholds may apply due to higher health risks at lower BMI levels.
NHS access is through specialist tier 3 weight management services — your GP can refer you, though waiting lists vary by region and can be lengthy. Private access is available through GPhC-registered online pharmacies following an online clinical assessment, without needing an NHS referral. Your GP can discuss which route is most appropriate for you and assess whether medication is suitable alongside diet and lifestyle changes.
- 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 lose weight with medication alone, without changing my diet?
Prescription weight loss medications work best alongside a reduced-calorie diet and increased physical activity. While medication helps reduce appetite, sustainable weight loss typically requires dietary changes and lifestyle adjustments. Your prescriber will discuss realistic expectations and how to support medication with healthy habits.
What's the difference between Mounjaro and Wegovy for weight loss?
Both are once-weekly injections approved for UK weight management. Mounjaro (tirzepatide) is a dual GIP/GLP-1 agonist with average weight loss of 15–21%. Wegovy (semaglutide) is a GLP-1 agonist with average weight loss around 15%. Both require prescription, and your prescriber will help determine which is most suitable for you.
How long does it take to see weight loss results with medication?
Weight loss typically begins within the first 4 weeks, with most significant progress in weeks 8–12 as doses increase. Results continue over several months. Individual timelines vary based on starting weight, dose, diet, and lifestyle. Your prescriber will monitor progress and adjust your treatment as needed.
Is weight loss medication available on the NHS in my area?
NHS access depends on your local integrated care board (ICB) and available specialist tier 3 weight management services. Ask your GP about referral options in your area. Many areas have waiting lists. Private options are available without NHS referral if you prefer faster access and meet clinical eligibility criteria.
What happens to weight if I stop taking weight loss medication?
Weight can return if medication is stopped without sustained lifestyle changes. Weight loss medications work best as part of a long-term approach that includes diet and activity changes. Your prescriber will discuss how to maintain results and whether ongoing medication is appropriate 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.