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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How to lose 3 stone: a practical UK health guide
Losing 3 stone (approximately 19 kg or 42 lbs) is an achievable goal for most UK adults, but it requires commitment to sustainable lifestyle changes. The NHS recommends losing weight gradually at a rate of 0.5 to 1 kg per week, which means losing 3 stone would typically take 5 to 9 months. This guide explains the evidence-based approaches to weight loss, including dietary changes, physical activity, and when prescription weight loss medication might be suitable alongside lifestyle modifications.
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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.
How much weight is 3 stone and what does it mean for your health?
3 stone equals approximately 19 kg or 42 lbs. For context, losing this amount can have meaningful health benefits even if it doesn't reach an "ideal" weight. According to NHS guidance, losing just 5–10% of your body weight can significantly improve blood pressure, blood sugar control, and reduce strain on joints. To understand where you stand now, use our free BMI calculator above to check your current weight category, and our weight converter to switch between stone, kg, and lbs easily. If you weigh 90 kg (14st 3lbs) and lose 3 stone, you'd reach approximately 71 kg (11st 2lbs) — potentially moving from an overweight to a healthy weight range depending on your height. The key is that sustainable weight loss requires both reduced calorie intake and increased physical activity, not rapid or extreme approaches.
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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.
Realistic methods for losing 3 stone: diet, exercise, and when to consider medication
Calorie deficit approach: To lose 0.5–1 kg per week, aim for a deficit of 500–1000 kcal per day. This typically means consuming around 1500–2000 kcal daily for most adults (exact amounts vary by age, sex, and activity level). Physical activity: Combine aerobic exercise (walking, cycling, swimming) with strength training to preserve muscle during weight loss. Prescription weight loss medication: For some adults, prescription treatments like GLP-1 injections (Mounjaro or Wegovy) may support weight loss efforts alongside dietary changes. These require a clinical assessment to confirm eligibility — typically a BMI of 30 or above, or 27+ with weight-related health conditions like type 2 diabetes or high blood pressure. Try our free GLP-1 weight loss calculator to explore potential outcomes with medication, and track your progress with our progress tracker.
- 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 long does it realistically take to lose 3 stone?
Following NHS guidance, losing 3 stone at a safe rate of 0.5–1 kg per week takes approximately 5–9 months. Faster weight loss is possible but increases risk of muscle loss and is typically only recommended under medical supervision.
What's the best diet for losing 3 stone?
The most effective diet is one you can sustain. Evidence supports calorie deficit approaches, Mediterranean-style eating, and low-carb diets for short-term loss. A 500 kcal daily deficit typically results in 0.5 kg weekly loss. Your GP can advise on options suited to your health.
Can prescription weight loss injections help me lose 3 stone?
Clinical trials show GLP-1 medications like Wegovy may support clinically studied weight loss on average — which for a 90 kg person is approximately 13.5 kg (just under 2 stone). They're prescription-only and work best alongside reduced calories and activity. Individual results vary significantly.
What health benefits come from losing 3 stone?
Losing 3 stone can reduce blood pressure, improve blood sugar levels, lower LDL cholesterol, ease joint pain, improve sleep apnoea, reduce cancer risk, and boost energy and mood. Even 5–clinically studied weight loss shows measurable health improvements.
Should I see my GP before trying to lose 3 stone?
Yes. Your GP can assess your overall health, rule out underlying conditions affecting weight, and discuss safe approaches for you personally. If you're considering prescription weight loss treatment, a clinical assessment is essential for safety and suitability.
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.