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 15.9 Lbs (7.2 kg) a Healthy Weight?
Converting 15.9 lbs to kg gives you 7.2 kg — but whether this is a healthy weight depends entirely on your height. A weight that's healthy for one person could be underweight for another. This guide explains healthy weight ranges for different heights using NHS guidelines, and shows you how to find out if your weight is right for your body. Use our free BMI calculator above to check your personal health status instantly.
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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 7.2 kg (15.9 lbs), your weight is very low and would be considered underweight for virtually all adults. To understand if your actual weight is healthy, you need to know your height and calculate your BMI.
Here are three real examples:
- At 160 cm (5ft 3in): 7.2 kg gives a BMI of 2.8 — severely underweight (healthy range: 18.5–24.9)
- At 175 cm (5ft 9in): 7.2 kg gives a BMI of 2.4 — severely underweight (healthy range: 18.5–24.9)
- At 185 cm (6ft 1in): 7.2 kg gives a BMI of 2.1 — severely underweight (healthy range: 18.5–24.9)
These examples show that 7.2 kg is below healthy weight at any height for an adult. If this is your current weight, speak to your GP, as it may indicate a health condition requiring support.
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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 Next
The NHS defines a healthy BMI as between 18.5 and 24.9 for most adults. At 7.2 kg, you're significantly below this range regardless of your height. This can indicate malnutrition, an eating disorder, or an underlying medical condition. Your GP can help determine the cause and provide appropriate support.
Waist circumference is also important: for men, over 94 cm indicates increased health risk; for women, over 80 cm. However, at this weight level, BMI is the primary concern. Don't delay — book an appointment with your GP to discuss your health and weight. They can refer you to specialist services if needed. Our weight converter can help you understand your weight in both metric and imperial units.
- 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.
How do I convert 15.9 lbs to kg?
Divide 15.9 by 2.20462, which equals 7.2 kg. You can use our free weight converter to switch between kilograms to stone, stones and lbs, and other metric to imperial weight conversions instantly.
At what height would 7.2 kg be a healthy weight?
7.2 kg would not be a healthy weight at any realistic adult height. A healthy BMI (18.5–24.9) requires a minimum weight of approximately 52 kg at 160 cm. Speak to your GP if you weigh 7.2 kg.
What does BMI mean and why does height matter?
BMI (Body Mass Index) combines your weight and height to estimate body fat. Height matters because the same weight is distributed differently across taller and shorter bodies. Use our free BMI calculator to find your personal BMI using your actual height.
Is being underweight as serious as being overweight?
Yes. Being significantly underweight can indicate malnutrition, eating disorders, or medical illness. It increases risk of weakened bones, infections, and poor organ function. GP support is important.
What should I do if I'm underweight?
Book an appointment with your GP to discuss your weight and health. They can identify causes and may refer you to a dietitian or specialist. Never attempt rapid weight gain without medical guidance.
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.