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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42 Kg In Stone And Pounds — Healthy Weight Guide
42 kg converts to 6 stone 8.1 pounds (or 6st 8lbs) in UK measurements. Whether this is a healthy weight depends entirely on your height — the same weight can be healthy for one person and underweight or overweight for another. This guide shows you how to check if 42kg is healthy for you using NHS guidelines, and what to do if you're concerned about your weight.
10,000+ calculations today · NHS-aligned thresholds · 100% free
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 — 42 Kg In Context
To convert 42kg to stone, divide by 6.35: 42 ÷ 6.35 = 6 stone 8 pounds. Whether this is healthy depends on your height. Here are three real examples showing how the same weight (42kg) sits differently on different bodies:
- At 5ft 0in (152cm): 42kg gives a BMI of 18.2 — healthy weight range
- At 5ft 4in (163cm): 42kg gives a BMI of 15.8 — underweight (below healthy range)
- At 4ft 10in (147cm): 42kg gives a BMI of 19.4 — healthy weight range
Use our free BMI calculator above to find your personal BMI at 42kg and your height, then compare it to NHS categories (healthy: 18.5–24.9). If you're at the lower end or outside the healthy range, consult your GP — underweight can also affect health.
Clinically BackedWeight Loss
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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: Is 42 Kg Healthy For You?
Healthy weight depends on height, age, muscle mass, and individual health. According to NHS guidelines, a BMI between 18.5 and 24.9 is considered healthy for most UK adults. At 42kg, you'll fall into this range if you're roughly between 4ft 10in and 5ft 4in tall. Waist measurement also matters: even at a healthy weight, a large waist circumference (over 80cm for women, 94cm for men) indicates increased health risk. If you're concerned about whether 42kg is right for you, your GP can assess your individual health context. Remember, healthy weight is personal — it's not about appearance, but about what supports your 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 42 kg in stone and pounds?
42 kg equals 6 stone 8.1 pounds (written as 6st 8lbs). To convert kilograms to stone, divide by 6.35. Our free weight converter above lets you instantly convert between kg, stone, and pounds for any weight.
Is 42 kg a healthy weight?
It depends on your height. Use the BMI calculator on this page to check your personal BMI at 42kg. If your BMI falls between 18.5 and 24.9, you're in the healthy range according to NHS guidelines. Shorter adults may be overweight at 42kg; taller adults may be underweight.
What is the healthy weight range for my height?
The healthy weight range varies by height. At 5ft 2in, healthy weight is roughly 47–63kg. At 5ft 6in, it's about 50–68kg. Use our BMI calculator to find the exact healthy range for your height, or speak to your GP for personalised guidance.
Why does height matter for weight?
Height affects how weight is distributed across your body. A taller person can carry more weight while maintaining the same BMI as a shorter person. That's why BMI (weight relative to height) is more reliable than weight alone for assessing health.
What should I do if 42 kg seems unhealthy for me?
If you're concerned about your weight — whether it seems too low or too high for your height — speak to your GP. They can assess your individual health, check your waist measurement, and advise whether any changes are needed. Never make drastic weight changes without professional 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.