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 Program for Weight Loss — UK Medication Options
A weight program for weight loss in the UK may include prescription medication alongside diet and activity changes. If you have a BMI of 30 or above, or a BMI of 27–29.9 with weight-related health conditions, you may be eligible for prescription weight management treatment. The NHS now funds certain GLP-1 medications through specialist services, whilst private options are also available. Understanding what's available can help you decide whether this approach suits your health goals.
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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 medications are currently licensed for weight loss in the UK: Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide). All work by activating GLP-1 (or dual GIP/GLP-1) pathways to reduce appetite and help you feel fuller after smaller meals.
- Mounjaro: Once-weekly injection, doses from 2.5 mg to 15 mg. Clinical trials showed average weight loss of 15–21% of body weight over 72 weeks alongside reduced-calorie diet and physical activity.
- Wegovy: Once-weekly injection, doses from 0.25 mg to 2.4 mg. STEP trials demonstrated average weight loss of approximately 15% of body weight at the maximum dose.
- Saxenda: Daily injection, doses from 0.6 mg to 3 mg. Established option with long clinical history for weight management support.
All are prescription-only and require a clinical assessment before dispensing. Individual results vary significantly. Try our free GLP-1 weight loss calculator to see projected outcomes at different doses based on your current weight.
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 in the UK
NHS access: NICE has approved prescription weight loss medications for NHS specialist weight management services (tier 3). You'll need a referral from your GP, typically to a hospital-based multidisciplinary team. Availability and waiting times vary by region (ICB area)—some areas have very long waiting lists.
Private access: Available through GPhC-registered online pharmacies following an online clinical assessment with a UK-licensed prescriber. No NHS referral required. Costs typically range from £129–£320 monthly depending on dose and provider.
Either route requires eligibility assessment. Use our free BMI calculator to check if you fall within typical thresholds (BMI ≥30, or ≥27 with comorbidities). Your GP can discuss which pathway is most suitable for you.
- 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.
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 a BMI of 27–29.9 with at least one weight-related health condition (type 2 diabetes, high blood pressure, cardiovascular disease, sleep apnoea, or dyslipidaemia). For South Asian, Chinese, Black African, or Black Caribbean adults, lower thresholds may apply. A GP or prescriber will assess your individual circumstances.
How much weight can I expect to lose with a weight loss program using medication?
Clinical trials show average weight loss of 15–21% of body weight depending on the medication and dose. Results vary significantly between individuals and depend on diet, physical activity, and individual metabolism. Medications support weight loss—they work best alongside reduced-calorie diet and increased physical activity, not instead of lifestyle changes.
What's the difference between Mounjaro and Wegovy?
Mounjaro (tirzepatide) is a dual GIP/GLP-1 agonist with a maximum weekly dose of 15 mg. Wegovy (semaglutide) is a GLP-1-only agonist with a maximum weekly dose of 2.4 mg. Clinical trial data suggest Mounjaro may support slightly greater average weight loss, but both are effective. Individual response varies, and suitability depends on personal health factors.
How do I start a weight loss program through the NHS?
Speak to your GP about weight management options. If appropriate, they may refer you to a specialist tier 3 weight management service. These multidisciplinary teams assess eligibility, discuss medication options, and provide ongoing support. Referral availability and waiting times vary by region—ask your GP about timescales in your area.
Can I get weight loss medication privately if I'm not eligible for NHS treatment?
Yes. Private online prescribing is available through GPhC-registered pharmacies for adults who meet eligibility criteria (BMI ≥30 or ≥27 with comorbidities). You complete an online consultation with a UK-licensed prescriber who assesses suitability. Private treatment is faster but costs more than NHS services. Always ensure you're using a legitimate, registered pharmacy. ```
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.