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
Is 19.5kg in Stone a Healthy Weight?
19.5kg converts to 1 stone and 5.5 pounds, but whether this is a healthy weight entirely depends on your height. A weight of 19.5kg is extremely light for most UK adults — for context, average adult weights range from 71kg to 86kg. This weight might be appropriate for a young child, but for adults, it would fall well below healthy ranges. Use our free BMI calculator above to check your personal health status, and read on to discover healthy weight ranges for different heights according to NHS guidelines.
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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.
Healthy Weight Ranges by Height (for 19.5kg Context)
At 19.5kg, this weight would only be considered healthy for a very young child. For adult perspectives, here are healthy weight ranges for different heights according to NHS BMI guidelines:
- 5ft 0in (152cm): Healthy weight is 45–57kg. At 19.5kg, you would be significantly underweight (BMI 8.4)
- 5ft 4in (163cm): Healthy weight is 49–66kg. At 19.5kg, BMI would be 7.3 — severely underweight
- 5ft 8in (173cm): Healthy weight is 55–74kg. At 19.5kg, BMI would be 6.5 — severely underweight
These ranges reflect NHS guidance for healthy BMI (18.5–24.9). If your actual weight is 19.5kg as an adult, or if you're supporting a child at this weight, speak with your GP urgently about nutritional support and health monitoring.
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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.
What the NHS Recommends If You're Underweight
Being significantly underweight carries health risks including nutritional deficiency, weakened immunity, bone density loss, and hormonal imbalances. The NHS recommends consulting your GP if you fall below a healthy weight range. Your GP can assess whether underlying causes exist — such as hypermetabolism, digestive conditions, eating difficulties, or mental health factors — and recommend appropriate support.
Record your weight regularly using our free progress tracker to monitor trends over time. If weight gain is needed, your GP may suggest nutritional supplements, referral to a dietitian, or specialist investigation. Remember: healthy weight isn't just a number — it's about having enough nutrition to fuel your body and maintain wellbeing.
- 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 is 19.5kg in stone and pounds?
19.5kg converts to 1 stone and 5.5 pounds (1st 5.5lbs). To convert kg to stone, divide by 6.35. This is a very low weight for adult populations and would only be typical for young children or infants, depending on age.
Is 19.5kg a healthy weight for an adult?
No. For any adult height, 19.5kg is far below healthy weight ranges. A healthy BMI (18.5–24.9) requires minimum weights of 45–55kg depending on height. At 19.5kg, all adults would be severely underweight. Please consult your GP for health assessment.
What is the healthy weight range for someone 5ft 6in tall?
At 5ft 6in (168cm), the healthy weight range is approximately 52–70kg according to NHS BMI guidelines. 19.5kg would result in a BMI of 6.9, indicating severe underweight status requiring medical evaluation.
Why does healthy weight depend on height?
BMI (the standard health measure) combines weight and height in a formula: BMI = weight(kg) ÷ height(m)². Taller people can be heavier while maintaining a healthy BMI; shorter people need less weight. This is why a single weight isn't universally "healthy" — context matters.
What should I do if I'm significantly underweight?
Contact your GP for assessment. Underweight status can signal nutritional deficiency, illness, or absorption issues. Your GP can identify causes and arrange dietitian support, nutritional supplements, or investigation as needed. Use our BMI calculator to track your health metrics.
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.