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 13.7 Kg A Healthy Weight?
13.7 kg converts to approximately 30.2 pounds. Whether this is a healthy weight depends entirely on your height. A weight that's healthy for a young child would be severely underweight for an adult. This guide shows you how to check if 13.7 kg falls within a healthy range for your height using NHS guidelines, and explains what to do if you're concerned about your weight. Use our free BMI calculator above to check your personal BMI instantly based on your height and weight.
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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 at Different Heights
At 13.7 kg, whether you're in a healthy weight range depends on your height. Here are three concrete examples:
- At 140 cm (4ft 7in): 13.7 kg gives a BMI of 7.0 — this is significantly underweight and would require medical attention, particularly in adults.
- At 110 cm (3ft 7in): 13.7 kg gives a BMI of 11.3 — still underweight for this height; would typically only be appropriate for a young child aged 8–10 years.
- At 80 cm (2ft 8in): 13.7 kg gives a BMI of 21.4 — this falls within the healthy range for a toddler or very young child, though individual growth charts should always be used for children.
For adults, a healthy BMI is between 18.5 and 24.9. Use the BMI calculator on this page to find your personal healthy weight range based on your exact height.
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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 13.7 kg as an adult, this is well below the healthy range and requires GP assessment. The NHS recommends that adults consult their GP if weight loss has been unintentional or if they're significantly below a healthy weight. Underweight status can indicate nutritional deficiency, underlying health conditions, or other concerns needing professional support.
If this weight applies to a child, your health visitor or GP should monitor growth using age-specific growth charts rather than adult BMI categories. Waist circumference is also important for health — NHS guidance suggests measurements under 94 cm (37 inches) for men and 80 cm (31.5 inches) for women indicate lower health risk. Speak to your GP for personalised advice about your weight and health.
- 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 13.7 kg in pounds?
13.7 kg converts to approximately 30.2 pounds (lbs). To calculate: multiply kilograms by 2.20462. So 13.7 × 2.20462 = 30.2 lbs. You can use our free weight converter on this page for instant conversions between kg, stone, and lbs.
Is 13.7 kg a healthy weight for an adult?
No, 13.7 kg is significantly underweight for any adult. Adults require much higher body weight for health — healthy weight ranges typically start at around 45–50 kg depending on height. If you weigh 13.7 kg, please consult your GP urgently.
Is 13.7 kg healthy for a child?
13.7 kg may be appropriate for a child aged approximately 8–10 years, depending on their exact height and individual growth pattern. Children's weight should always be assessed using age-specific NHS growth charts, not adult BMI categories. Your health visitor or GP can advise if your child's weight is healthy.
How do I convert kg to stone easily?
To convert kilograms to stone, divide the kilogram amount by 6.35. For example, 13.7 kg ÷ 6.35 = 2.16 stone. Our weight converter on this page converts between kg, stone, and lbs instantly — simply enter your weight in any unit.
What should I do if I'm underweight?
If you're significantly underweight, consult your GP. They can assess whether weight loss has been unintentional, check for underlying health conditions, and recommend support. Underweight status can indicate nutritional deficiency or other health concerns needing professional attention.
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.