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
Understanding Weight and Healthy Weight Management
Weight management is about maintaining a healthy body weight that supports your long-term health and wellbeing. In the UK, we measure weight using stone, pounds, and kilograms, and the NHS provides clear guidance on healthy weight ranges based on your height. This guide explains what constitutes a healthy weight, how to assess your own weight status, and the evidence-based approaches to weight management that actually work. Whether you're looking to understand your current weight or considering making changes, having accurate information is the first step.
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 is a Healthy Weight in the UK?
A healthy weight is defined using Body Mass Index (BMI), which is calculated from your height and weight. According to NHS guidance, a healthy BMI for most UK adults is between 18.5 and 24.9. This means your weight is in a range that supports good health and reduces the risk of weight-related conditions like type 2 diabetes, heart disease, and high blood pressure.
However, healthy weight varies significantly between individuals depending on factors including muscle mass, bone density, age, and ethnic background. For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower BMI thresholds, with a healthy range starting at 18.5 to 22.9, as research shows these groups face higher health risks at the same weight as other populations.
- Use our free BMI calculator above to check your personal BMI instantly
- Our weight converter helps you understand your weight across kg, stone, and pounds
- A healthy weight range supports better sleep, energy, and cardiovascular health
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 Management Approaches and NHS Guidance
The NHS supports a stepped approach to weight management, starting with self-help and lifestyle changes before considering specialist support. Weight loss should be gradual and sustainable — the NHS recommends losing no more than 0.5 to 1 kg per week (roughly 1 to 2 pounds). This rate minimises muscle loss and makes changes easier to maintain long-term.
For many people, sustainable weight management combines a modest calorie deficit (around 500 kcal per day), increased physical activity, and behavioural changes. If you're concerned about your weight or struggling to manage it through lifestyle alone, your GP can refer you to specialist weight management services in your area. Some individuals may be eligible for prescription weight loss treatment through the NHS, depending on their BMI and health conditions.
- 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 BMI should I aim for?
A healthy BMI for most UK adults is 18.5 to 24.9, according to NHS guidelines. For people of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends 18.5 to 22.9. Use our free BMI calculator to find your personal BMI — it's the starting point for understanding your weight health.
How quickly can I lose weight safely?
The NHS recommends losing 0.5 to 1 kg (1 to 2 pounds) per week for sustainable, healthy weight loss. This typically requires a calorie deficit of around 500 kcal per day and makes changes easier to stick to long-term. Faster weight loss can lead to muscle loss and is harder to maintain.
Does BMI apply to everyone?
BMI is useful as a screening tool but has limitations. It doesn't distinguish between muscle and fat, so athletes may have a high BMI but low body fat. BMI is also less accurate during pregnancy and in elderly people. Your GP can discuss whether BMI is the right measure for your individual situation.
What weight-related health conditions qualify for NHS support?
If your BMI is 27 to 29.9 with a weight-related health condition, you may qualify for NHS specialist support. These conditions include type 2 diabetes, prediabetes, high blood pressure, sleep apnoea, or previous heart attack or stroke. Your GP can assess your eligibility and refer you to local tier 3 weight management services.
Can I use the weight converter to check different units?
Yes — our free weight converter on this page lets you instantly convert between kilograms, stone, and pounds. This is useful for understanding your weight in whichever units feel most natural to you, and for comparing your weight to NHS guidelines and health information published in different formats.
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.