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
Weight Loss in the UK — Your Complete Health Guide
Weight loss is a journey toward better health and vitality, not just a number on the scales. Whether you're looking to manage your weight through lifestyle changes, prescription medication, or a combination of approaches, the NHS recommends a structured approach tailored to your individual circumstances. This guide covers evidence-based weight management strategies available to UK adults, including how to calculate your current health status using your BMI, sustainable dietary changes, and prescription options if appropriate. At MyWeightCheck, we provide free tools to help you understand your starting point and track your progress every step of the way.
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.
How to Lose Weight Safely — NHS-Recommended Approaches
The NHS recommends safe weight loss of 0.5 to 1 kg per week for sustainable, long-term results. Faster weight loss can lead to muscle loss and is harder to maintain. A calorie deficit of around 500 kcal per day typically supports this rate of loss.
- Dietary changes: Focus on whole foods, vegetables, lean proteins, and reducing ultra-processed foods. A Mediterranean-style diet has strong evidence for both weight management and cardiovascular health.
- Physical activity: Aim for at least 150 minutes of moderate activity weekly, plus resistance training twice weekly to protect muscle mass during weight loss.
- Behavioural support: The NHS offers free weight loss programmes, behaviour change support, and digital tools through tier 1 and 2 weight management services.
Use our free BMI calculator to understand your current health status, and the weight converter to track progress in stone, pounds, or kilograms — whichever feels most natural to you.
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.
Weight Loss Medication Options Available in the UK
For adults with a BMI of 30 or above, or 27 or above with weight-related health conditions, prescription weight loss medications may be offered alongside lifestyle changes. GLP-1 medications like Wegovy (semaglutide) work by reducing appetite and helping you feel fuller after smaller meals.
Wegovy is available through NHS specialist weight management services or private prescription following clinical assessment. In clinical trials, participants lost an average of approximately 15% of their body weight — though individual results vary significantly. These medications are prescription-only and require ongoing assessment to ensure they remain appropriate for you. Try our GLP-1 weight loss calculator to explore potential outcomes 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.
What's the difference between weight loss and healthy weight loss?
Weight loss achieved through crash dieting or extreme measures is often temporary and can harm your health. Healthy weight loss follows NHS guidance: 0.5–1 kg per week, alongside balanced nutrition and activity. This approach preserves muscle, supports metabolism, and is more sustainable long-term. Rapid loss often leads to regain once the strict phase ends.
Can I get weight loss medication on the NHS?
Yes, if eligible. Adults with a BMI of 30 or above, or 27+ with weight-related conditions like type 2 diabetes, may be referred to NHS tier 3 specialist weight management services. From there, medications like tirzepatide (Mounjaro) or semaglutide (Wegovy) may be offered. However, access and waiting times vary significantly by region. Your GP can advise on local services.
What is a healthy BMI, and how do I know mine?
The NHS defines a healthy BMI as 18.5 to 24.9 for most UK adults. For South Asian, Chinese, Black African, and Black Caribbean adults, a lower threshold of 18.5–22.9 is recommended due to higher health risks at standard BMI levels. Use our free BMI calculator to find your personal BMI — it takes just seconds and gives you clear context.
How long does weight loss take to show health benefits?
Evidence suggests that losing even 5% of your body weight can improve blood pressure, blood sugar control, and reduce joint strain. You may feel benefits like improved energy and better sleep within weeks. For significant cardiovascular improvements, 10–15% loss over several months is typical. Progress tracking helps you see non-scale wins too.
Is weight loss medication a replacement for diet and exercise?
No. Weight loss medications work best alongside reduced-calorie diet and increased physical activity. Medications help reduce appetite and support behaviour change, but they are not a standalone solution. Once medication is stopped, weight regain can occur without sustained lifestyle changes. This is why comprehensive support matters most.
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.