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 and Age Chart — UK Health Guidance
A weight and age chart helps you understand whether your current weight is healthy for your age, height, and sex. In the UK, the NHS uses BMI (Body Mass Index) as the primary screening tool rather than age-specific weight ranges alone, because BMI accounts for both weight and height. Age can influence metabolism, muscle mass, and nutritional needs, but the same healthy BMI ranges (18.5–24.9 for most adults) apply regardless of age. Use our free BMI calculator to find your personal healthy weight range, then discuss the results with your GP if you have concerns about weight management or health changes with age.
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.
NHS Approach to Weight Across Age Groups
The NHS doesn't publish age-specific weight charts for adults because healthy weight depends on your height, not your age. Instead, the NHS recommends using BMI as a universal screening tool. However, age does matter when thinking about weight health:
- Young adults (18–30): Metabolism is typically highest; healthy BMI remains 18.5–24.9. This is the ideal time to establish healthy habits.
- Middle-aged adults (30–65): Metabolism naturally slows by approximately 2–8% per decade. Weight gain becomes more common without dietary or activity adjustments. The same healthy BMI range applies, but maintaining it may require more active effort.
- Older adults (65+): Muscle mass naturally decreases with age. A slightly higher BMI may be protective, but discuss with your GP. Underweight (BMI below 18.5) carries higher risks in this age group.
For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower BMI thresholds regardless of age due to higher cardiovascular risk at the same BMI.
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.
Finding Your Healthy Weight Range
Rather than relying on age-based weight charts, calculate your personalised healthy weight range using your height. The healthy BMI range (18.5–24.9) translates to specific weight in kg or stone depending on how tall you are. For example, an adult who is 1.70m tall has a healthy weight range of approximately 53–72 kg (8st 5lbs–11st 5lbs). Use our free BMI calculator above to instantly determine your healthy weight range in both kg and stone. If you're concerned about your weight or experience changes in weight despite stable eating and activity habits, speak with your GP—this could indicate underlying health conditions like thyroid issues, which are more common with age.
- 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.
Is there a standard weight chart by age in the UK?
No. The NHS uses BMI (Body Mass Index) as the primary health screening tool for all adults, regardless of age. BMI takes both your weight and height into account, making it more accurate than age-alone charts. The healthy BMI range (18.5–24.9) applies universally, though older adults should discuss results with their GP.
Why does metabolism change with age?
Metabolism naturally slows by approximately 2–8% per decade after age 30, primarily due to loss of muscle mass. Muscle tissue burns more calories at rest than fat tissue. This means maintaining weight becomes harder without adjusting diet or increasing physical activity. Regular strength training can help preserve muscle mass and metabolism.
Is it normal to gain weight as you get older?
It's common but not inevitable. Age-related weight gain often results from slowed metabolism and reduced physical activity rather than age itself. With consistent healthy eating and regular exercise (including strength training), many adults maintain stable weight throughout life. Consult your GP if weight changes seem unexplained.
What's a healthy weight range for someone in their 50s?
A healthy BMI remains 18.5–24.9 at any age, including your 50s. Your specific healthy weight in kg or stone depends on your height. Use our BMI calculator to find your personalised range. Your GP can advise if age-related factors like medications or health conditions affect your weight.
Should older adults aim for the same healthy BMI as younger adults?
Generally yes, though your GP may advise differently based on your individual health. Some research suggests a slightly higher BMI (up to 27) may be protective in older adults, but this varies. Discuss your personal healthy weight range with your GP, especially if you have existing health conditions.
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.