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
NHS Diet Pills and Weight Loss Options in the UK
The NHS offers a range of weight management approaches beyond diet pills alone. Depending on your BMI, health conditions, and circumstances, you may be eligible for free lifestyle support, specialist services, or prescription medication through the NHS. Understanding your options helps you choose the safest and most effective path to sustainable weight loss. This guide covers everything available to UK adults, from tier 1 self-help support through to specialist weight management services.
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.
Weight Loss Options Available Through the NHS
The NHS weight management pathway is structured in four tiers, each offering different levels of support:
- Tier 1 (Self-help & Community): Free weight loss programmes like the NHS Weight Loss Plan, digital apps, community weight management groups, and online behaviour change support available to all adults.
- Tier 2 (Primary Care): Support through your GP, including advice on nutrition, physical activity, and behaviour change. GPs can refer you to structured programmes or signpost to local services.
- Tier 3 (Specialist Services): Multidisciplinary weight management services provided by specialist teams. This is where prescription weight loss medication — including GLP-1 medications like semaglutide (Wegovy) and tirzepatide (Mounjaro) — may be initiated, alongside dietary and behavioural support.
- Tier 4 (Bariatric Surgery): Surgical options considered for severe obesity with significant comorbidities, typically BMI ≥40 or ≥35 with weight-related health conditions.
Most adults start at tier 1 or 2. Referral to tier 3 specialist services typically requires your GP to assess that you meet clinical criteria.
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.
How to Choose the Right Weight Loss Approach for You
The most effective weight loss approach is one you can sustain long-term. Consider your BMI, any weight-related health conditions (such as type 2 diabetes or high blood pressure), your lifestyle, and your preference for support structure. Use our free BMI calculator to understand your current health category. If you have a BMI of 30 or above, or 27–29.9 with weight-related health conditions, discuss specialist weight management support with your GP. For sustainable weight loss, aim for 0.5–1 kg per week through a combination of dietary changes and increased physical activity. Our GLP-1 weight loss calculator can help you understand potential outcomes if prescription medication 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 first step to accessing NHS weight loss support?
Contact your GP to discuss your weight and health. Your GP can assess whether you're eligible for tier 2 support, refer you to local community programmes, or refer you to specialist tier 3 services if needed. They can also discuss whether prescription weight loss medication might be appropriate based on your BMI and health conditions.
Are prescription weight loss injections available on the NHS?
Yes. Prescription weight loss medications (GLP-1 injections like Wegovy and dual GIP/GLP-1 injections like Mounjaro) are available through NHS tier 3 specialist weight management services. Access and waiting times vary significantly by region. Your GP can refer you to your local specialist service for assessment.
How long does it take to access NHS specialist weight management services?
Waiting times vary considerably depending on your local NHS integrated care board (ICB). Some regions have waiting lists of several months to over a year. Tier 1 and tier 2 support (self-help and GP-based) are typically accessible much more quickly. Ask your GP about local availability when you request a referral.
Can I access prescription weight loss medication privately if I don't want to wait for NHS services?
Yes. Prescription weight loss medications are available through private online prescribing services if you meet clinical eligibility criteria. A UK-licensed prescriber will assess your health and issue a prescription if appropriate, which can be dispensed by a GPhC-registered pharmacy. Costs vary by medication and dose.
What if I'm not eligible for prescription medication — what are my other options?
Tier 1 and tier 2 NHS support focus on sustainable lifestyle changes: reduced-calorie diet (typically 500 kcal/day deficit for 0.5 kg/week loss), increased physical activity, and behaviour change support. Evidence shows that even 5–clinically studied weight loss can significantly improve health markers. Digital apps, community programmes, and GP-guided behaviour change are all evidence-based and free through the NHS. ```
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.