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
Chart For Age And Weight — What's Healthy?
There is no single "healthy weight chart for age" in the UK — weight depends on height, not age. The NHS uses BMI (body mass index) to assess whether someone is at a healthy weight, regardless of age. BMI ranges stay the same for adults throughout life, though muscle mass naturally decreases with age. Our free BMI calculator can help you find whether your current weight falls into the healthy range for your height. Individual health also depends on where weight is stored and other factors beyond just the number on the scales.
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 Guidance On Healthy Weight For Adults
The NHS does not use age-based weight charts for adults. Instead, it uses BMI (body mass index), which is calculated from your height and weight and applies equally to all adults.
- Healthy BMI range: 18.5–24.9 (all ages)
- Overweight: 25.0–29.9
- Obese (Class I): 30.0–34.9
- Obese (Class II): 35.0–39.9
- Severely obese (Class III): 40.0 and above
For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower thresholds — a healthy BMI starts at 18.5 but overweight begins at 23.0 rather than 25.0. Waist circumference also matters: men should aim for under 94cm (37 inches), and women under 80cm (31.5 inches). Use our free BMI calculator above to check your personal BMI instantly and see where you fall on the NHS healthy weight scale.
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.
Age, Metabolism, And Weight Management
While healthy BMI ranges don't change with age, your body composition and metabolism do. As adults age, muscle naturally decreases and fat increases, even at the same weight. This is why weight management becomes more important over 40 — maintaining muscle through physical activity and adequate protein helps sustain a healthy metabolism.
The NHS recommends regular strength training and at least 150 minutes of moderate activity per week for all adults, adapted for mobility and fitness level. Our free weight converter can help you track progress in your preferred units (kg, stone, or pounds), and if you're working on weight loss, our GLP-1 weight loss calculator can help estimate potential outcomes with structured diet and exercise changes. Always speak to your GP if you're concerned about your weight or health at any 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 an age-based weight chart for UK adults?
No. The NHS uses BMI (body mass index) for all adults regardless of age. BMI is calculated from height and weight, not age. A healthy BMI is 18.5–24.9 for all adults, though lower thresholds apply to certain ethnic groups. Your GP can advise on healthy weight for your individual health profile.
Why doesn't the NHS use age-based weight charts?
Age alone doesn't determine healthy weight. Height is what matters for BMI calculation. However, age does affect metabolism, muscle mass, and how your body stores fat. Older adults benefit from strength training to maintain muscle and metabolic health, even if their target weight range (BMI) stays the same.
What's the healthy weight range for a 50-year-old woman who is 165cm tall?
At 165cm (5ft 5in), a healthy BMI range is 18.5–24.9. This equals roughly 50–68kg (7st 12lbs to 10st 10lbs). This range applies at age 30, 50, or 70 — BMI doesn't change with age. Use our BMI calculator above to find your exact healthy range, and speak to your GP about weight management tailored to your health needs.
Does metabolism slow down with age, affecting weight?
Yes. Metabolism slows by roughly 2–8% per decade after age 30, partly because muscle naturally decreases. However, regular physical activity and strength training help maintain muscle and metabolism at any age. The healthy weight (BMI) target stays the same, but maintaining it may require more deliberate effort as you age.
Where can I find personalised healthy weight advice for my age and health?
Your GP is the best starting point. They can discuss your individual health, any weight-related conditions, and create a personalised plan. The NHS also offers free digital weight management tools and community programmes. MyWeightCheck's free BMI calculator and weight converter can help you understand your current position relative to NHS guidelines anytime.
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.