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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Free Weight Loss Meal Plan with UK Prescription Options
A structured meal plan is the foundation of sustainable weight loss, but for many UK adults, prescription weight management medication can provide additional support. If you have a BMI of 30 or above, or 27 or above with weight-related health conditions, you may be eligible for licensed prescription weight loss treatment alongside dietary changes. This guide explains the UK-approved medications available, who qualifies, and how to discuss options with your GP. Combined with a reduced-calorie meal plan and increased physical activity, these medications can help support meaningful weight loss when self-directed approaches need additional help.
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 Options
Three prescription medications are currently licensed for weight management in the UK:
- Mounjaro (tirzepatide) — a dual GIP and GLP-1 receptor agonist available as a once-weekly injection. Clinical trials showed participants lost an average of 15–21% of their body weight over 72 weeks, though individual results vary significantly.
- Wegovy (semaglutide) — a GLP-1 receptor agonist given once weekly. In clinical trials, average weight loss was approximately 15% of body weight at the maximum dose.
- Saxenda (liraglutide) — a GLP-1 receptor agonist given as a daily injection, less commonly used in recent years.
All three are prescription-only medicines requiring assessment by a licensed prescriber. They are not alternatives to a meal plan or exercise — they work alongside lifestyle changes. Our free GLP-1 weight loss calculator can help you estimate potential results at different doses based on clinical trial data.
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 vs Private Access and Getting Started
In the UK, NHS access to prescription weight loss treatment is through specialist tier 3 or tier 4 weight management services — not standard GP prescription. Waiting lists can be lengthy and availability varies by region (Integrated Care Board). Many people access these medications privately through a GPhC-registered online pharmacy following an online clinical assessment and prescription from a UK-licensed prescriber.
To find out if you're eligible: Start by calculating your BMI using our free BMI calculator above. If your BMI is 30 or above, or 27–29.9 with weight-related conditions like type 2 diabetes, high blood pressure, or sleep apnoea, you may qualify. Discuss options with your GP, who can assess your individual health and refer you to NHS specialist services if appropriate.
- 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 just a free meal plan without medication?
Yes. A calorie deficit of around 500 kcal per day, combined with increased physical activity, typically results in approximately 0.5 kg loss per week. The NHS recommends this sustainable approach as the first step. Prescription weight loss medication is only for those who meet eligibility criteria and where a prescriber judges it appropriate.
What is the difference between Mounjaro and Wegovy?
Mounjaro (tirzepatide) is a dual GIP and GLP-1 agonist; Wegovy (semaglutide) is a GLP-1 agonist only. Mounjaro showed slightly higher average weight loss in trials (15–21% vs approximately 15%), but both are effective. Choice depends on individual factors assessed by your prescriber.
Am I eligible for NHS weight loss medication?
Potentially, if you have a BMI of 30 or above, or 27 or above with weight-related health conditions such as type 2 diabetes, hypertension, or sleep apnoea. Ethnicity-adjusted thresholds apply for South Asian, Chinese, Black African, and Black Caribbean adults. Your GP can assess your eligibility and refer you to specialist services.
How much does prescription weight loss medication cost privately in the UK?
Private costs typically range from approximately £129–£320 per month depending on the medication, dose, and provider. This is separate from NHS provision. Prices vary between GPhC-registered online pharmacies, so it's worth comparing options.
Do weight loss injections work without a meal plan?
No. Prescription weight loss medications like Mounjaro and Wegovy are designed to be used alongside a reduced-calorie meal plan and increased physical activity. They are not standalone treatments. Clinical trial results were achieved by participants who combined medication with dietary and lifestyle changes.
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.