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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How to Record Your Weight Accurately
Recording your weight consistently is one of the most effective ways to monitor your health and track progress towards your weight management goals. Whether you're following NHS guidance, using a weight loss programme, or simply managing your general health, keeping accurate weight records helps you spot trends and stay motivated. This guide explains the best practice methods for recording weight in the UK, including when to weigh yourself, what to expect from fluctuations, and how to use your data meaningfully alongside other health indicators like BMI and waist circumference.
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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.
Best Practice for Recording Weight Accurately
Timing matters when recording your weight. Weigh yourself at the same time each day for consistency — early morning after using the toilet and before eating or drinking is ideal, as this eliminates variables like food and water content. Use the same scales each time if possible, as different scales can show variations of 1–2 kg. The NHS recommends weighing yourself weekly rather than daily, as daily fluctuations are normal and can be demoralising. Weight naturally varies by 1–2 kg day-to-day depending on hydration, food intake, hormones, and digestion.
- Weigh yourself weekly on the same day (e.g., every Monday morning)
- Use the same scales in the same location
- Wear similar clothing or no clothing for consistency
- Record your weight immediately after weighing
- Track in both kg and stone if you prefer UK measurements
- Note the date and time for reference
Our free weight converter helps you switch between kg, stone, and pounds instantly, making it easy to record in whichever unit you prefer. For a fuller picture of your health, use our free BMI calculator alongside weight recording — BMI provides important context about whether your weight is within a healthy range for your height.
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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.
Recording Weight During Weight Loss or Weight Management
If you're following a structured weight loss programme or using NHS healthy weight guidance, recording weight becomes a key accountability tool. Expect fluctuations rather than a smooth downward line — this is completely normal and doesn't mean the programme isn't working. The NHS recommends aiming for weight loss of 0.5 to 1 kg per week for sustainable results. If you're tracking weight loss with medication like Mounjaro or Wegovy, weight recording helps you and your prescriber assess whether the treatment is effective for you. Our free GLP-1 weight loss calculator can help project potential weight loss at different doses, giving you realistic expectations.
- Record weekly, not daily, to avoid demoralisation
- Expect 2–3 kg fluctuations due to water retention and hormones
- Look at trends over 4 weeks, not single measurements
- Share records with your GP or prescriber if requested
- Use our progress tracker to log and visualise your journey over time
- 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 record my weight?
The NHS recommends weighing yourself weekly rather than daily. Daily fluctuations due to food, water, and hormones are normal and can be misleading. Choose one day per week (e.g., Monday morning) and record at the same time for consistency. Weekly recording keeps you accountable without obsessive monitoring.
What time of day is best to weigh yourself?
Early morning after using the toilet and before eating or drinking is ideal. At this time, your weight is typically at its lowest and least affected by food and water content. Use the same time each day to ensure consistency, which makes trends more meaningful.
Does weight fluctuation mean my diet or medication isn't working?
No. Normal daily weight fluctuations of 1–2 kg are caused by hydration, food intake, hormones, and digestion — not fat loss or gain. Look at trends over 4 weeks rather than day-to-day changes. The NHS considers sustainable weight loss to be 0.5 to 1 kg per week. If you're using weight loss medication, your prescriber will assess effectiveness based on overall trends, not individual measurements.
Should I record weight in kg or stone for accuracy?
Either unit is accurate — choose whichever you prefer. Use our free weight converter to switch between kg, stone, and pounds. Record in the same unit each time for consistency. The NHS uses kilograms clinically, but UK adults often prefer stone and pounds. Both work equally well for tracking trends.
How do I know if my recorded weight is in a healthy range?
Use your height and recorded weight to calculate your BMI using our free BMI calculator on this page. A BMI of 18.5 to 24.9 is considered healthy by NHS guidelines. For South Asian, Chinese, Black African, or Black Caribbean adults, a healthy range is 18.5 to 22.9. Your GP can provide personalised advice about what's healthy for you.
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.