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
45 Kg — What It Means for Your Health in the UK
45 kg is a relatively light weight for most UK adults, but what it means for your individual health depends on your height, age, and overall fitness. Using NHS guidance, we'll help you understand whether 45 kg falls within a healthy weight range for you and what this means in familiar UK measurements. Whether you're tracking your own health or supporting someone else, understanding weight in context is the first step towards making informed decisions about wellbeing.
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.
Understanding 45 Kg in UK Context
In UK measurements, 45 kg equals approximately 7 stone and 1 pound (7st 1lb). However, whether this weight is healthy depends entirely on your height. The NHS uses BMI (body mass index) as a screening tool to assess weight in relation to height. For example, at 160 cm (5ft 3in), a weight of 45 kg would give a BMI of approximately 17.6, which falls within the healthy weight range of 18.5 to 24.9. Conversely, at 150 cm (4ft 11in), the same weight would give a BMI of around 20, still healthy. However, at 170 cm (5ft 7in), 45 kg would result in a BMI of approximately 15.6, which falls below the healthy range and may indicate being underweight.
BMI is a useful initial screening tool recognised by the NHS, but it has important limitations — it does not account for muscle mass, bone density, or where fat is stored. Your GP can provide personalised guidance on whether your weight is appropriate for your individual circumstances.
Clinically BackedWeight Loss
No appointments. No waiting rooms. Just care — from a UK-regulated online pharmacy.
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.
Using UK Tools to Check Your Health Status
The best way to understand what 45 kg means for your specific health is to use our free BMI calculator, which instantly shows your personal BMI category based on your height and weight. Simply enter your measurements, and you'll receive NHS-aligned guidance on whether you fall into the healthy, underweight, overweight, or obese category.
If you're tracking weight changes or working towards a health goal, our free weight converter and progress tracker can help you monitor your journey in your preferred units — whether that's kg, stone, or pounds. For young people under 18, BMI categories differ from adults and use age and sex-specific growth charts; always consult NHS resources or your GP for guidance on children's weight.
- 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 45 kg in stone and pounds?
45 kg equals 7 stone and 1 pound (7st 1lb). To convert, divide 45 by 6.35029 to get stone. Use our free weight converter to switch between kg, stone, and pounds instantly with full accuracy.
Is 45 kg a healthy weight?
Whether 45 kg is healthy depends on your height. At 160 cm, a BMI of around 17.6 is healthy. At 150 cm, it's still healthy at BMI 20. At 170 cm, it would be underweight at BMI 15.6. Use our BMI calculator to check your personal BMI and NHS category instantly.
What is the healthy weight range at 45 kg?
The healthy weight range depends on your height. At 160 cm, the healthy range is approximately 47–63 kg. At 170 cm, it's 53–72 kg. Your GP can discuss whether 45 kg is appropriate for your individual health and circumstances.
Is 45 kg underweight for an adult?
At some heights, yes — for example, at 170 cm (5ft 7in), 45 kg would be underweight with a BMI below 18.5. At other heights like 150 cm (4ft 11in), it falls within the healthy range. Height is crucial. Check your personal BMI using our free calculator.
Should I be concerned about being 45 kg?
Not necessarily — it depends on your height, muscle mass, overall fitness, and medical history. If you have concerns about whether your weight is healthy, contact your GP, who can assess your individual circumstances and provide personalised advice based on your complete health picture.
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.