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 Weight Loss Advice for UK Adults
The NHS provides clear, evidence-based guidance on losing weight safely and sustainably. Whether you're looking to manage your weight through lifestyle changes alone or exploring prescription weight loss medication, the NHS pathway offers support at every stage. This guide explains what the NHS recommends, how to access help, and what realistic weight loss looks like for most people.
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.
What Does the NHS Recommend for Weight Loss?
The NHS recommends losing weight at a rate of 0.5 to 1 kg (1 to 2 lbs) per week for sustainable, healthy results. This typically requires a calorie deficit of around 500 kcal per day. The NHS weight management pathway is structured across four tiers:
- Tier 1: Self-help using digital tools, apps, and community weight management programmes
- Tier 2: Primary care-based support through your GP, including behaviour change programmes like the NHS Weight Loss Plan
- Tier 3: Specialist multidisciplinary weight management services, where prescription weight loss medications may be considered
- Tier 4: Bariatric (weight loss) surgery for severe obesity with significant health complications
Most people start at Tier 1 or 2. Your GP can assess which tier is most appropriate for you. Use our free BMI calculator to check where you currently stand — this will help you understand which NHS pathway may be relevant to your situation.
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.
Prescription Weight Loss Medication on the NHS
The NHS has approved tirzepatide (Mounjaro) and semaglutide (Wegovy) for weight management through specialist tier 3 services. These are prescription-only GLP-1 and GLP-1/GIP receptor agonist medications that may help reduce appetite and support weight loss alongside diet and exercise. Eligibility typically requires a BMI of 30 or above, or 27–29.9 with weight-related health conditions such as type 2 diabetes or high blood pressure. NHS access varies significantly by region and waiting lists can be substantial in many areas. Your GP can refer you to a specialist weight management service for assessment. If you want to explore potential weight loss outcomes, try our GLP-1 weight loss calculator to see projected results at different doses.
- 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.
How much weight can I expect to lose following NHS advice?
Results vary significantly based on individual factors, diet adherence, and activity level. Following the NHS 0.5–1 kg per week guideline, you could lose 2–4 kg per month. Over 6 months, this could mean 6–24 kg of weight loss. Even a 5–10% reduction in body weight has meaningful health benefits, such as improved blood pressure and blood sugar control. Individual results depend on your starting point, metabolism, and commitment to lifestyle changes.
Do I need to see my GP before starting weight loss?
It's advisable to speak with your GP before starting any significant weight loss programme, especially if you have existing health conditions, take medications, or are considering prescription weight loss treatment. Your GP can assess whether weight loss is appropriate for you, check for any contraindications, and potentially refer you to tier 2 or 3 support services. If you're simply making dietary changes, you can start independently, but a GP check-in is always recommended for personalised advice.
What's the difference between NHS and private weight loss medication access?
NHS access to prescription weight loss medication (Mounjaro, Wegovy) is through specialist tier 3 weight management services following GP referral. Availability and waiting times vary by region. Private access is available through online consultations with UK-licensed prescribers and GPhC-registered pharmacies, without NHS referral. Private options are faster but involve direct costs (typically £130–£320 per month depending on dose). Both require clinical assessment; neither is available over-the-counter.
Can I use our weight converter or BMI calculator to track my progress?
Yes. Our free weight converter helps you switch between kg, stone, and lbs — useful if your GP discusses your weight in different units. The BMI calculator lets you check your current BMI against NHS guidelines and see how it changes as you lose weight. For detailed progress tracking over weeks and months, our free progress tracker allows you to log your weight regularly and visualise your weight loss journey alongside your goals.
What if I'm not eligible for NHS weight loss medication?
If you don't meet NHS criteria (BMI below 27–30 depending on comorbidities), you can still lose weight effectively through lifestyle changes recommended by Tier 1 and 2 NHS services. These include calorie deficit, dietary approaches like the Mediterranean diet, increased physical activity, and behaviour change support. You can also explore private prescription weight loss options if you meet clinical eligibility criteria assessed by a private prescriber. Your GP can advise on what's appropriate for your individual circumstances.
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.