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 Chart For Weight — UK Health Context
Healthy weight varies by age, height, and individual health factors rather than age alone. In the UK, the NHS uses BMI (body mass index) as the primary screening tool for healthy weight across all adult age groups, regardless of age. This guide explains how age relates to weight management, what NHS guidance recommends, and how to find your healthy weight range using UK health information. Age does influence metabolism and body composition, but healthy weight targets remain consistent across the adult lifespan.
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 NHS Defines Healthy Weight Across Ages
The NHS does not publish separate weight charts by age for adults — instead, healthy weight is determined by height and BMI, which applies consistently from age 18 onwards. A healthy BMI ranges from 18.5 to 24.9 for most UK adults. For adults of South Asian, Chinese, Black African, or Black Caribbean backgrounds, the NHS recommends a lower threshold of 18.5 to 22.9 due to increased health risks at higher BMI levels in these groups.
Your healthy weight range depends on your height, not your age. For example, a 40-year-old and a 70-year-old who are both 5ft 8in tall have the same healthy weight range of approximately 55–75 kg (8st 9lbs–11st 11lbs). What changes with age is metabolism, muscle mass, and activity levels — these affect how easily you maintain weight, but not what the target should be. Our free BMI calculator above shows your personal healthy weight range instantly based on your height.
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 Metabolism and Body Composition Change With Age
After age 30, muscle mass naturally declines by approximately 3–5% per decade (sarcopenia). Since muscle burns more calories than fat, this metabolic slowdown means weight management often requires more intentional effort in older age. Additionally, hormonal changes — particularly after the menopause in women — can affect fat distribution and weight stability.
However, these changes do not alter your healthy weight target. The NHS healthy weight guidance remains the same. Maintaining or achieving a healthy BMI throughout your life reduces risks of type 2 diabetes, cardiovascular disease, and certain cancers at any age. If you're finding weight management more challenging as you age, your GP can discuss realistic, sustainable approaches tailored to 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.
Should I aim for a different weight now I'm over 60?
No. The NHS healthy weight range (BMI 18.5–24.9) applies to all adults regardless of age. What may change is how you achieve and maintain that weight — your GP can advise on realistic approaches that account for your current activity level and health status. Use our free BMI calculator to find your personal healthy range.
Is it normal to gain weight as you get older?
Weight gain with age is common due to reduced muscle mass, lower activity levels, and metabolic changes — but it is not inevitable. Staying active, eating nutritious foods, and strength training can help preserve muscle and maintain a stable weight. If weight gain is concerning you, discuss sustainable options with your GP.
What is the average weight for UK adults by age?
Average weight varies widely within age groups and depends on height and individual factors. Rather than aiming for an "average," it's more helpful to use your personal BMI or healthy weight range based on your height, which you can calculate using our free weight management tool on this page.
Do older adults need to lose weight more slowly?
The NHS recommends a sustainable rate of 0.5–1 kg per week for all adults. Faster loss increases muscle loss risk and is harder to maintain. Older adults benefit from gradual, sustained approaches combined with strength training to preserve muscle mass. Always discuss weight loss plans with your GP, especially if you're taking medications.
How do I convert my target weight between kg and stone?
Use our free weight converter above to switch instantly between kilograms, stone, and pounds. For example, if your healthy range is 55–75 kg, the converter shows this as approximately 8st 9lbs to 11st 11lbs in UK measurements. Understanding your target in both units can make tracking easier.
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.