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
What Does a Weight Loss Expert Recommend?
A weight loss expert in the UK is typically a GP, registered dietitian, or specialist within the NHS weight management services who can assess your individual health and recommend the most appropriate approach for you. Whether that's lifestyle changes, prescription weight loss medication, or referral to specialist support depends on your BMI, health conditions, and personal circumstances. The NHS provides structured weight management through a tiered system, while private options including GLP-1 weight loss injections are also available following clinical assessment. Your starting point is always a conversation with your GP about what's right for your situation.
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.
NHS Weight Management Pathway and Professional Support
The NHS weight management pathway has four tiers of support, each building on the previous one. Tier 1 involves self-help and community programmes you can access yourself — think digital tools, apps, and local weight loss groups. Tier 2 brings in your GP and structured behaviour change programmes like the NHS Weight Loss Plan. Tier 3 is where specialist multidisciplinary teams — including dietitians, psychologists, and specialist doctors — provide intensive support and may prescribe weight loss medication such as GLP-1 injections or orlistat. Tier 4 covers bariatric surgery for severe obesity with significant health complications.
A weight loss expert working through the NHS typically focuses on sustainable change: a calorie deficit of around 500 kcal per day can support losing approximately 0.5 kg per week, which the NHS considers safe and sustainable. Use our free BMI calculator above to understand where you fall on the NHS scale, and our weight converter to track your progress in measurements you understand — whether that's stone, kilograms, or pounds.
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 Options and Clinical Assessment
If lifestyle changes alone aren't sufficient, a weight loss expert may recommend prescription weight loss medication. In the UK, GLP-1 weight loss injections like Wegovy (semaglutide) and Mounjaro (tirzepatide) are prescription-only and available through NHS specialist services or private prescribing following clinical assessment. These medications work by activating natural appetite-regulating hormones; clinical trials showed average weight loss of 15–21% of body weight alongside reduced-calorie diet and increased physical activity — though individual results vary significantly.
Eligibility typically requires a BMI of 30 or above, or 27 or above with weight-related health conditions such as type 2 diabetes or high blood pressure. Our free GLP-1 weight loss calculator can help you explore potential outcomes at different doses. Your prescriber will assess whether prescription weight loss is appropriate for you based on your full health picture, not just your weight.
- 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 qualifications does a weight loss expert have?
In the UK, weight loss experts include GPs, registered dietitians (RD), specialist obesity doctors, and nurses working within NHS tier 3 weight management services. Dietitians are regulated by the Health and Care Professions Council (HCPC). Always check credentials — look for RD after their name or ask if they're registered with RCCP or REPS UK.
How do I access a weight loss expert on the NHS?
Start by speaking to your GP, who can assess your needs and refer you to tier 2 or tier 3 weight management services depending on your situation. NHS availability varies by region — some areas have long waiting lists. Private options are also available through GPhC-registered online prescribing services.
Can a weight loss expert prescribe Mounjaro or Wegovy on the NHS?
Yes, but only through NHS specialist (tier 3) weight management services. Mounjaro and Wegovy are prescription-only and eligibility is based on BMI and health conditions. Your GP can refer you, but access varies significantly by region and current NHS capacity.
What's the difference between a weight loss expert and a slimming club?
A weight loss expert (GP, dietitian, or specialist doctor) provides personalised medical assessment and can prescribe medication if appropriate. Slimming clubs offer peer support and behavioural coaching but aren't regulated healthcare providers and cannot prescribe medication.
How much weight loss should I expect with expert guidance?
The NHS recommends 0.5–1 kg per week as a safe, sustainable rate. With prescription GLP-1 medication alongside lifestyle changes, clinical trials showed average losses of 15–21% of body weight over several months — but individual results vary. A weight loss expert will set realistic goals based on your personal health profile.
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.