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
Best Weight Loss Diet for UK Adults
Finding the best weight loss diet depends on your individual health, lifestyle, and eligibility for support. The NHS recommends sustainable weight loss of 0.5 to 1 kg per week through reduced-calorie eating combined with increased physical activity. For eligible adults with a BMI of 30 or above, or 27 or above with weight-related health conditions, prescription weight loss medication may be available alongside dietary changes. This guide covers evidence-based diet approaches and UK weight management options to help you understand what works best for your situation.
10,000+ calculations today ยท NHS-aligned thresholds ยท 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/mยฒ).
While BMI isn't a perfect measure โ it doesn't account for muscle mass, bone density, or fat distribution โ 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 โ 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
If you're looking for weight management UK support beyond diet alone, three prescription-only medications are licensed in the UK for adults who meet eligibility criteria:
- Mounjaro (tirzepatide) โ dual GIP and GLP-1 injection, maximum dose 15 mg once weekly. Clinical trials showed average weight loss of 15โ21% body weight alongside diet and exercise.
- Wegovy (semaglutide) โ GLP-1 injection, maximum dose 2.4 mg once weekly. Evidence suggests average weight loss of approximately 15% body weight.
- Saxenda (liraglutide) โ daily GLP-1 injection, up to 3 mg per day. An established option for weight loss medication nhs and private access.
All three are prescription-only and require a clinical assessment before being prescribed. Individual results vary significantly, and these are used alongside, not instead of, dietary and lifestyle changes.
Clinically BackedWeight Loss
No appointments. No waiting rooms. Just care โ 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 โ 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 โ completely free.
NHS vs Private Access โ How to Get Started
NHS route: Your GP can refer you to a specialist tier 3 weight management service if you meet eligibility criteria. NHS weight loss services assess your individual health and may recommend lifestyle support, behavioural programmes, or in some cases, prescription medication. Availability and waiting times vary significantly by region.
Private route: Licensed prescribers offer online consultations followed by prescriptions dispensed by GPhC-registered pharmacies. This path doesn't require an NHS referral but is a private cost.
Start by discussing weight management uk goals with your GP, who can assess your BMI weight loss needs and advise on the best option for your circumstances.
Use our free BMI calculator above to check whether your weight falls into a category where prescription support might be appropriate, then discuss the results with your GP. Our GLP-1 weight loss calculator can help you estimate potential outcomes at different medication doses if you're considering prescription options. Track progress over time using our free progress tracker โ consistency matters whether you're managing weight through diet alone or with medication support.
- 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 โ 5mg โ 7.5mg โ 10mg โ 12.5mg โ 15mg
- GLP-1 receptor agonist
- Up to 15โ17% body weight loss (STEP trials)
- Weekly injection, 5-step dose escalation
- NHS & private prescription available
- Doses: 0.25mg โ 0.5mg โ 1mg โ 1.7mg โ 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 | 15โ22.5% | 12โ17% |
| Key trial | SURMOUNT-1 (2022) | STEP 1 (2021) |
| Max dose | 15 mg weekly | 2.4 mg weekly |
| Escalation period | 20โ32 weeks | 16โ20 weeks |
| Administration | Weekly injection (pen) | Weekly injection (pen) |
| NHS availability | Private prescription only | NHS & private |
| Approx. private cost | ยฃ150โยฃ250/month | ยฃ150โยฃ300/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 โ 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's the best diet for weight loss in the UK?
The best weight loss diet is one you can sustain long-term. The NHS recommends creating a calorie deficit of around 500 kcal per day for gradual, sustainable loss of 0.5โ1 kg weekly. Mediterranean, low-carbohydrate, and intermittent fasting approaches all have evidence supporting weight loss. Focus on whole foods, reduced portion sizes, and consistency rather than rapid restriction.
Am I eligible for prescription weight loss medication 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 weight-related health conditions such as type 2 diabetes, high blood pressure, or cardiovascular disease. South Asian, Chinese, Black African, and Black Caribbean adults may have lower thresholds. Your GP can assess your individual eligibility.
How much weight can I expect to lose with Mounjaro or Wegovy?
Clinical trials showed average weight loss of 15โ21% body weight with Mounjaro and approximately 15% with Wegovy, alongside a reduced-calorie diet and exercise. However, individual results vary significantly. Some people lose more, some less. Results depend on adherence, diet, activity level, and individual metabolism.
Can I get weight loss injections through the NHS?
Yes, Mounjaro and Wegovy are available through NHS specialist tier 3 weight management services if you're referred by your GP and meet eligibility criteria. However, NHS availability and waiting times vary greatly by region. Private online prescribing is also available as an alternative route without NHS referral.
What's the difference between diet-only weight loss and using prescription medication?
Prescription weight loss medication may help reduce appetite and support feeling fuller, making it easier to stick to a reduced-calorie diet. However, medication alone doesn't cause weight loss โ it works alongside dietary changes and exercise. The best approach combines whatever method you choose (diet, medication, or both) with sustained 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.