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
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Weight Checking: A UK Health Guide
Weight checking is a straightforward way to monitor your health, but understanding what your weight means is more important than the number itself. In the UK, weight management is about assessing your overall health using multiple measures—not just the scale. This guide explains how to check your weight properly, understand your healthy weight range, and know when to seek guidance from your GP. We'll cover UK measurements, NHS health thresholds, and practical steps for tracking your progress.
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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 Check Your Weight Effectively
The best approach to weight checking involves consistency and context. Weigh yourself at the same time each day, ideally in the morning before eating or drinking, using the same scales to reduce measurement variation. However, weight fluctuates naturally due to hydration, hormones, food intake, and digestive content—so don't be alarmed by daily changes of up to 1–2 kg.
- Weekly tracking: Record your weight once per week rather than daily to see genuine trends
- Use UK measurements: Most NHS guidance uses kilograms, but you can convert between kg, stone, and pounds easily with our free weight converter
- Combine with other measures: Weight alone doesn't tell the full story; waist circumference and how you feel physically matter too
- Consider your BMI: Calculate your BMI using our free BMI calculator to see where your weight sits within NHS healthy weight ranges
The NHS recommends that healthy weight management focuses on sustainable changes rather than gradual weight management. A loss of 0.5–1 kg per week is considered safe and realistic for most people.
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.
Understanding Your Healthy Weight Range
Your healthy weight depends on your height, age, sex, and muscle mass. According to NHS guidance, a healthy BMI falls between 18.5 and 24.9 for most UK adults, though lower thresholds apply for people of South Asian, Chinese, Black African, or Black Caribbean heritage due to higher health risks at lower BMI levels.
Rather than targeting a specific number, focus on a healthy weight range for your height. For example, at 5ft 8in (173 cm), a healthy weight range is approximately 55–74 kg (8st 10lbs to 11st 10lbs). Use our free BMI calculator to find your personal healthy range, and discuss your individual health goals with your GP, especially if you have existing health conditions.
Weight checking should be part of a broader approach to health management. Track changes over weeks and months rather than obsessing over daily fluctuations. If you're concerned about your weight or health, your GP can provide personalised guidance and, if appropriate, discuss weight management support including lifestyle changes or prescription medication options. Monitor your weight, but remember that numbers are just one aspect of overall wellbeing.
- 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 often should I check my weight?
Weekly weight checking is ideal for tracking genuine trends. Daily weighing can be misleading because of natural water retention, food intake, and hormonal fluctuations. Choose one day per week, same time of day (ideally morning), using the same scales for consistency.
What's a healthy weight range for my height in the UK?
A healthy BMI (18.5–24.9) varies by height. Use our free BMI calculator to find your personalised range in kg, stone, and pounds. For example, at 5ft 8in, healthy weight is roughly 55–74 kg (8st 10–11st 10lbs). NHS guidance also considers ethnicity—lower ranges apply for South Asian, Chinese, Black African, and Black Caribbean adults.
Why does my weight fluctuate so much day to day?
Daily weight changes are normal and usually not fat loss or gain. Factors include hydration levels, food intake, digestive content, hormones, salt consumption, and exercise-related inflammation. This is why weekly or monthly tracking is more useful than daily checks.
Should I weigh myself if I'm trying to lose weight?
Yes, but use it as one tool among several. Combine weight checks with progress photos, how clothes fit, energy levels, and measurements like waist circumference. The NHS recommends losing 0.5–1 kg per week as a safe, sustainable rate. Track progress over weeks, not days.
When should I talk to my GP about weight management?
Contact your GP if you're concerned about your weight, have experienced sudden weight changes, or if weight is affecting your health or mobility. Your GP can assess your BMI, discuss any underlying health conditions, and offer support including lifestyle advice or, if appropriate, specialist weight management services or medication options.
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.