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
Free tracker included with every download this week
Weight Loss Medication Available in the UK
While supplements like folic acid support overall health, prescription weight management medications offer clinically proven support for significant weight loss. If you're interested in weight management in the UK, several prescription options are available to eligible adults through both NHS and private routes. This guide explains what's available, who qualifies, and how to find out if prescription weight loss is right for you.
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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 weight loss medications are currently licensed in the UK for weight management: Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide). Both Mounjaro and Wegovy are once-weekly injections that work by activating GLP-1 hormone pathways, helping to reduce appetite and support feeling fuller after meals.
In clinical trials, these medications demonstrated significant results. Mounjaro users lost an average of 15–21% of body weight over 72 weeks, while Wegovy users lost approximately 15% on average. Saxenda is a daily injection with similar effectiveness. Eligibility for prescription weight loss medication depends on BMI and health factors:
- BMI of 30 or above (obesity)
- BMI of 27–29.9 (overweight) with at least one weight-related health condition such as type 2 diabetes, high blood pressure, or cardiovascular disease
- Adults of South Asian, Chinese, Black African, or Black Caribbean heritage may have lower BMI thresholds due to increased health risk at lower weights
Individual results vary significantly, and all medications work best alongside dietary changes and increased physical activity.
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 — What's Right for You
In the UK, weight loss injections are accessible through two main routes. NHS access is provided through specialist tier 3/4 weight management services following referral from your GP. However, NHS availability varies significantly by region, and waiting lists can be lengthy—some areas have waits of several months or longer. Private access is available through GPhC-registered online pharmacies following a clinical assessment with a UK-licensed prescriber, usually without NHS referral.
The first step is talking to your GP about whether prescription weight loss might be appropriate for you. Your GP can discuss your BMI, health conditions, and personal weight loss goals, then either refer you to NHS specialist services or advise you on private options. Use our free BMI calculator to check your current BMI before your appointment—it helps you have an informed conversation with your healthcare provider.
If you're already managing your weight through lifestyle changes, our GLP-1 weight loss calculator can help you estimate potential results if prescription medication becomes appropriate for you. Track your progress over time with our free progress tracker tool, whether you choose dietary changes, exercise, or medication-supported weight management.
- 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.
Is folic acid alone helpful for weight loss?
Folic acid is an important B vitamin supporting overall health and energy metabolism, but it is not a weight loss medication. While adequate folic acid intake supports healthy weight management practices, significant weight loss typically requires a calorie deficit combined with lifestyle changes or, for eligible adults, prescription medication alongside diet and exercise.
What's the difference between Mounjaro and Wegovy for weight loss?
Both are once-weekly injections licensed for weight management in the UK. Mounjaro (tirzepatide) activates dual GIP and GLP-1 pathways and showed average weight loss of 15–21% in trials. Wegovy (semaglutide) activates GLP-1 only and showed average weight loss of approximately 15%. Both require prescription and clinical assessment. Your GP or prescriber will determine which, if any, is appropriate for you.
How do I access weight loss medication on the NHS?
Ask your GP for a referral to your local tier 3 specialist weight management service if you meet eligibility criteria (BMI 30+ or 27–29.9 with weight-related health conditions). NHS provision varies significantly by region. If NHS waiting times are long or you're not eligible, private prescribing through a UK-licensed prescriber is an alternative option.
Can I use the weight loss calculator on this site to estimate my results?
Yes. Our free GLP-1 weight loss calculator helps you project potential weight loss at different medication doses based on clinical trial data. Remember that individual results vary significantly—the calculator shows averages alongside a reduced-calorie diet and increased physical activity, not assured outcomes.
What should I discuss with my GP about weight loss medication?
Bring your current BMI (calculate it here using our BMI calculator), your weight loss goals, any weight-related health conditions you have, and any medications you're currently taking. Your GP will assess whether prescription weight loss is suitable and either refer you to NHS services or advise you on private options available in the UK.
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.