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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What Is The Good Weight For My Height And Age?
There is no single "good weight" — it depends on your height, age, genetics, muscle mass, and overall health. The NHS defines a healthy weight using BMI (body mass index), which ranges from 18.5 to 24.9 for most adults. However, your ideal weight is personal. Use our free BMI calculator to find your healthy weight range, and remember that age affects metabolism and body composition, so what's healthy at 25 differs from what's healthy at 55. Your GP can give personalised guidance based on your individual health profile.
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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.
NHS Guidance On Healthy Weight For Your Height
The NHS uses BMI (body mass index) as the primary tool to assess whether weight is healthy for a given height. Your BMI is calculated by dividing weight in kilograms by height in metres squared.
For most UK adults, a healthy BMI falls between 18.5 and 24.9. However, if you're of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower thresholds — a healthy BMI for these groups is 18.5 to 22.9, as research shows higher health risks at elevated BMI levels in these populations.
To find your healthy weight range for your height:
- Lower bound = 18.5 × (height in metres)²
- Upper bound = 24.9 × (height in metres)²
For example, if you're 5ft 8in (1.73m), a healthy weight range is approximately 55–74kg (8st 10lbs to 11st 10lbs). Age doesn't change your BMI category, but it does affect how your body responds to diet and exercise, metabolism, and muscle loss. A healthcare professional can advise on what's optimal for you as an individual.
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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.
Why Age And Body Composition Matter
While BMI is useful, it has limitations. BMI doesn't distinguish between muscle and fat — an athlete with high muscle mass may have a high BMI but low body fat percentage. Age affects this significantly. As we age, we naturally lose muscle (sarcopenia), so two people with the same weight and height at different ages may have very different body compositions.
Body composition — the ratio of muscle to fat — is often more important than BMI alone. Factors like strength training, genetics, hormones, medical conditions, and medications all influence your ideal weight. This is why your GP may recommend looking beyond BMI and considering waist circumference (important for cardiovascular health) or discussing weight in the context of your personal health goals rather than a fixed number.
- 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.
What's the healthy weight range for a 5ft 6in woman?
For a woman 5ft 6in (168cm) tall, a healthy BMI (18.5–24.9) corresponds to a weight range of approximately 52–69kg (8st 3lbs to 10st 12lbs). Use our free weight converter to check specific weights in stone and pounds. However, your ideal weight depends on your age, muscle mass, and individual health factors — your GP can advise further.
Does healthy weight change as you get older?
Your BMI healthy range (18.5–24.9) doesn't officially change with age according to NHS guidelines. However, age does affect body composition — you naturally lose muscle mass as you age, which changes how your body looks and functions at the same weight. Metabolism also slows slightly with age, so maintaining the same weight may require more physical activity. Your GP can discuss age-specific health goals with you.
Is BMI accurate for everyone?
BMI is useful but has limitations. It doesn't account for muscle mass, bone density, or where fat is stored. For example, athletes, very muscular individuals, and older adults (who lose muscle) may have a high BMI but good health. BMI is also less accurate during pregnancy. For a fuller health picture, your GP might also consider waist circumference, blood pressure, and blood glucose levels.
How do I find my healthy weight using the BMI calculator?
Use our free BMI calculator on this page — enter your height and weight, and it will instantly show your BMI category and healthy weight range. The calculator uses NHS guidelines and works with metric or imperial measurements (kg, stone, or pounds). It also shows you how far you are from the healthy BMI range if your current weight falls outside it.
Should I aim for the middle of the healthy weight range?
Not necessarily. The healthy BMI range (18.5–24.9) is broad because different people thrive at different weights within it. Factors like muscle mass, bone structure, age, and personal health history mean someone at BMI 22 and someone at BMI 24 can both be healthy. Rather than targeting a specific number, focus on sustainable healthy habits — balanced nutrition, regular movement, adequate sleep, and stress management. Your GP can help you set realistic, personalised goals.
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.