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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Is 17.5 Kilos a Healthy Weight?
17.5 kilos converts to approximately 38.6 pounds. Whether this weight is healthy depends entirely on your height—a weight that's underweight for one person might be overweight for another. This guide shows you how to check if 17.5kg (or 38.6 lbs) falls within a healthy range for your height using NHS guidelines, plus practical steps to understand your personal weight status. Use our free BMI calculator above to find your exact BMI instantly, or read on for healthy weight ranges by height.
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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
At 17.5kg, you're at a very low body weight. To understand if this is healthy for you, we need to look at height. The NHS healthy weight range is a BMI of 18.5 to 24.9 for most UK adults.
Here are three real-world examples showing how height changes whether 17.5kg is healthy:
- Height 4ft 6in (137cm): 17.5kg gives a BMI of 9.3 — this is severely underweight and would need urgent medical attention.
- Height 5ft 0in (152cm): 17.5kg gives a BMI of 7.6 — also severely underweight and medically concerning.
- Height 5ft 6in (168cm): 17.5kg gives a BMI of 6.2 — critically underweight across all heights.
At 17.5kg, this weight would be considered dangerously low for virtually all adults. A healthy weight range typically starts much higher depending on your height and build.
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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.
NHS Guidance and What to Do
If you weigh 17.5kg or are significantly underweight, it's important to speak with your GP as soon as possible. Being severely underweight can be associated with malnutrition, bone health problems, and other medical concerns that need professional assessment.
The NHS recommends checking your waist circumference alongside weight—waist measurement matters for health risk too. If you're concerned about your weight being too low or too high, your GP can provide personalised advice about a healthy weight range for your individual height, age, and health profile. Use our weight converter to track your weight in different units as you work towards a healthier range.
- 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 17.5 kilos in pounds exactly?
17.5 kilos equals 38.58 pounds (often rounded to 38.6 lbs). To convert kilograms to pounds, multiply by 2.20462. This conversion applies anywhere—it's the standard metric to imperial weight conversion used worldwide, including in the UK.
Is 17.5kg a healthy weight for adults?
At 17.5kg, this weight is dangerously low for all adult heights and would be considered severely underweight. A healthy weight depends on height, but generally starts much higher. If you weigh this little, speak to your GP urgently about your health.
How do I know if my weight is healthy for my height?
Use the BMI calculator on this page to find your exact BMI. The NHS healthy range is 18.5 to 24.9. You can also convert your weight using stone and pounds to see it in UK measurements, then compare against NHS healthy weight ranges for your height.
What's the healthy weight range for someone 5ft 6in tall?
For 5ft 6in (168cm), the healthy weight range is approximately 50–68kg (7st 12lbs to 10st 10lbs). This gives a BMI between 18.5 and 24.9. Your GP can advise on the ideal weight for your individual circumstances.
When should I contact my GP about my weight?
Contact your GP if you're significantly underweight, losing weight unintentionally, or concerned about your health. Being very underweight—like 17.5kg—needs urgent medical assessment to rule out underlying health issues or nutritional deficiencies.
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.