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 Menu: UK Prescription Medication Options
A weight loss menu in the UK now includes several prescription medication options alongside traditional diet and exercise approaches. If you're considering weight management, understanding what's available through the NHS and private prescribing can help you make an informed decision with your GP. This guide covers the main prescription weight loss options available to eligible UK adults, how they work, and how to access them.
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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
The UK currently has three main prescription medications licensed for weight management: Mounjaro (tirzepatide), a dual GIP and GLP-1 receptor agonist; Wegovy (semaglutide), a GLP-1 receptor agonist; and Saxenda (liraglutide), another GLP-1 option given as a daily injection. These glp-1 weight loss medications work by helping regulate appetite and reducing food cravings. Clinical trials showed average weight loss ranging from approximately 15% to 21% of body weight over 68–72 weeks, though individual results vary significantly.
- Mounjaro: Once-weekly injection, doses from 2.5 mg to 15 mg, may offer the highest average weight loss
- Wegovy: Once-weekly injection, doses up to 2.4 mg, well-established clinical evidence
- Saxenda: Daily injection, maximum 3 mg, longer history of use in weight management
All three are prescription-only medicines available only following a clinical assessment. They are typically used alongside a reduced-calorie diet and increased physical activity — medication alone is not considered sufficient for effective weight loss.
Clinically BackedWeight Loss
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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 Prescribing
NHS access to prescription weight loss medication is through specialist tier 3 and tier 4 weight management services, usually requiring a GP referral. Availability varies significantly by region and ICB. NHS eligibility typically requires a BMI of 30 or above, or BMI 27–29.9 with a weight-related health condition such as type 2 diabetes, high blood pressure, or sleep apnoea. Private prescribing is available without NHS referral through GPhC-registered online pharmacies following a clinical assessment. Your GP can help you understand which route suits your situation and whether you meet eligibility criteria for nhs weight loss medication. Use our free BMI calculator to check your starting point, and speak with your healthcare provider about whether prescription weight management is appropriate 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.
What is the difference between Mounjaro and Wegovy for weight loss?
Mounjaro (tirzepatide) activates two hormone pathways (GIP and GLP-1), while Wegovy (semaglutide) activates one (GLP-1 only). Clinical trials showed Mounjaro achieved approximately 20.9% average weight loss at maximum dose versus Wegovy's 14.9%. Both are once-weekly injections. Individual results vary, and your prescriber will advise which is more suitable for you.
Am I eligible for prescription weight loss medication on the NHS?
NHS eligibility generally requires a BMI of 30 or above, or 27–29.9 with weight-related conditions like diabetes or high blood pressure. South Asian, Chinese, Black African, and Black Caribbean adults may have access at lower BMI thresholds. Your GP can assess your individual eligibility and refer you to specialist weight management services if appropriate.
How quickly will I lose weight on these medications?
Clinical trials showed average weight loss of 0.5–1 kg per week alongside reduced-calorie diet and exercise. However, individual results vary significantly — some people lose more, some less. Weight loss typically plateaus after 12–16 weeks at each dose level. Your prescriber will monitor progress and adjust your dose as needed.
Can I get these weight loss medications privately without an NHS referral?
Yes. Private prescribing is available through GPhC-registered online pharmacies following a clinical assessment by a UK-licensed prescriber. You do not need an NHS referral. Costs vary by dose and provider but typically range from £129–£320 per month. Always ensure any private prescriber is properly registered with the General Pharmaceutical Council.
What happens if I stop taking weight loss medication?
Weight loss medication works alongside lifestyle changes. If you stop taking it without maintaining the diet and exercise changes you've made, weight loss may plateau or reverse. Your prescriber will discuss what to expect if you discontinue treatment and how to maintain any progress you've made.
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.