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
Age and Weight Charts — What's Healthy for UK Adults?
Age and weight charts help you understand whether your current weight is healthy for your age, height, and sex. However, there's no single "ideal weight" that applies to everyone — health depends on many individual factors. The NHS uses BMI (body mass index) as the primary screening tool for healthy weight ranges, which applies regardless of age. This guide explains how age and weight relate to health outcomes and what you should focus on instead of a fixed chart number.
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.
How Age Affects Healthy Weight Ranges
Age itself doesn't change your healthy weight range — BMI categories remain the same across all adults. However, age does affect how your body composition changes. As you get older, you naturally lose muscle mass and may gain fat mass even if your total weight stays the same. This means an older adult at the same BMI as a younger adult may actually have higher body fat percentage.
- Adults aged 18–65: standard NHS BMI categories apply (18.5–24.9 = healthy weight)
- Adults aged 65+: muscle loss is more common, so weight management becomes more important for strength and mobility
- Younger adults (18–30): establishing healthy habits now reduces disease risk later
Rather than relying on age-based weight charts, use our free BMI calculator above to check your personal BMI, which is the NHS recommended screening tool for all adults. Your GP can also assess your individual health in context of your age, medical history, and fitness level.
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.
Why Age and Weight Charts Can Be Misleading
Traditional age and weight charts often suggest different "ideal weights" for different ages, but this approach oversimplifies health. These charts don't account for muscle mass, bone density, fitness level, ethnicity, or medical conditions — all of which significantly affect what weight is healthy for you personally.
A person with high muscle mass (like an athlete) may have a "high" BMI but excellent health. Someone at the same BMI with low fitness may have different health risks. Instead of following a chart, focus on: measuring your waist circumference (NHS recommends under 94cm for men, under 80cm for women), your BMI range, and how you feel physically. If you're concerned about your weight and health, your GP can provide personalised guidance based on your individual circumstances.
- 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 recommended weight for my age?
The NHS does not recommend different BMI ranges by age — healthy BMI (18.5–24.9) applies to all adults aged 18–65. However, your GP may consider your individual health, fitness, and medical history when discussing weight with you. Age-based weight charts can be misleading because they ignore muscle mass and body composition.
What weight is healthy for a 40-year-old woman?
Healthy weight depends on your height, not age alone. Use the BMI calculator on this page with your height and weight to find your personal range. For example, at 5ft 6in (168cm), a healthy weight range is approximately 52–70kg (8st 2lbs to 11st 0lbs). Your GP can advise what's healthiest for you specifically.
Do I need to weigh less as I get older?
No — BMI categories don't change with age. However, maintaining a healthy weight becomes increasingly important for mobility, bone health, and preventing disease as you age. Muscle loss is common after 65, so strength training alongside weight management is particularly valuable in older adulthood.
Can I use a weight chart to check if I'm overweight?
Age and weight charts are less accurate than BMI. Instead, calculate your BMI using our free tool above or the NHS BMI calculator — this gives you a personalised result based on your height and weight. Your GP can also assess your individual health context beyond just a number on a chart.
What if my weight is higher than the chart suggests but my BMI is healthy?
BMI is more reliable than age-based charts. If your BMI falls in the healthy range (18.5–24.9 according to NHS guidance), your weight is likely appropriate for your height — charts can underestimate healthy weight for taller or more muscular individuals. Use our weight converter and BMI calculator together to get a fuller picture of your health.
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.