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 Advice for UK Adults
Losing weight successfully requires a combination of sustainable dietary changes, increased physical activity, and realistic expectations about timeframes. The NHS recommends losing weight at a rate of 0.5 to 1 kg per week for the best long-term results. This guide covers the most effective weight management strategies available in the UK, from lifestyle changes to prescription options, helping you understand what approach might work best for your situation and health goals.
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.
Evidence-Based Weight Loss Methods That Work
The most effective weight loss approaches combine calorie deficit with sustainable lifestyle changes. A deficit of around 500 kcal per day typically results in approximately 0.5 kg per week loss. The NHS weight loss plan recommends a balanced, calorie-controlled diet rather than restrictive approaches.
- Mediterranean diet — strong evidence for cardiovascular health and sustainable weight management
- Low carbohydrate diets — effective short-term, though long-term outcomes are similar to calorie restriction
- Intermittent fasting — evidence supports modest weight loss for some people
- Regular physical activity — at least 150 minutes moderate activity weekly, plus strength training
For UK weight management, calculate your BMI first using our free BMI calculator to understand your current health category. Even losing 5–10% of your body weight produces meaningful health benefits including lower blood pressure, improved blood sugar control, and reduced joint pain.
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.
When to Consider Prescription Weight Loss Support
If lifestyle changes alone haven't worked, prescription weight loss medication may help. The NHS offers access through specialist tier 3 weight management services, though regional availability varies and waiting lists can be lengthy. GLP-1 weight loss medications like semaglutide (Wegovy) and tirzepatide (Mounjaro) are prescription-only and available through NHS specialist services or private online prescribing.
These medications may help reduce appetite and support feeling fuller with smaller meals. Clinical trials showed average weight loss of 14–21% body weight when combined with dietary changes and exercise. Private options are available without NHS referral, following an online clinical assessment with a licensed prescriber. Try our free GLP-1 weight loss calculator to explore projected results at different medication 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 is the healthiest rate of weight loss?
The NHS recommends losing 0.5 to 1 kg per week for sustainable results. This rate reduces muscle loss and is more likely to result in lasting changes. Faster weight loss can be unsafe without medical supervision and often leads to regaining the weight.
What's the difference between BMI and actual body composition?
BMI is a screening tool but doesn't distinguish between muscle and fat — athletes may have high BMI but low body fat. Our free weight converter and BMI calculator help put your weight in context, but waist measurement and overall fitness also matter for health.
How do GLP-1 weight loss injections work in the UK?
GLP-1 medications like Wegovy are prescription-only and activate hormones that reduce appetite and support fullness. They're available through NHS specialist services or private prescribing following clinical assessment. Individual results vary; they work best alongside reduced-calorie diet and increased activity.
Can I access weight loss medication through the NHS?
Yes, through specialist tier 3 weight management services via GP referral. Eligibility requires BMI 30+ or 27+ with weight-related conditions like diabetes. Regional variation and waiting lists mean private options are also available. Your GP can discuss which route suits you best.
What should I do first if I want to lose weight?
Calculate your current BMI and set realistic goals — aim for 0.5–1 kg per week loss. Start with dietary changes and increased physical activity. Track your progress using our free progress tracker. If lifestyle changes aren't working after 3 months, discuss prescription options with your GP. ```
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.