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
What Is Adjusted Body Weight?
Adjusted body weight is a calculation used in healthcare to estimate a more accurate weight for medical purposes, particularly when standard body weight may not reflect a person's actual body composition. It's especially useful in the UK where health professionals need precise measurements for medication dosing, clinical assessments, and personalised weight management guidance. Unlike your actual measured weight, adjusted body weight accounts for differences in muscle mass, bone density, and fat distribution—giving a clearer picture of your health profile than weight alone.
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.
How Adjusted Body Weight Is Calculated
Adjusted body weight is calculated using a formula that combines your actual measured weight with your ideal body weight. The basic formula is: Adjusted Body Weight = Ideal Body Weight + (Actual Body Weight − Ideal Body Weight) × 0.4. This means adjusted weight is roughly 40% of the difference between your actual and ideal weight, added to your ideal weight.
- Ideal body weight is typically estimated using formulas like the Devine or Robinson formula, which account for your height and sex
- The adjustment factor (0.4 or 40%) helps account for excess fat mass without overstating it
- This calculation is particularly useful when actual weight differs significantly from ideal weight—common in weight management scenarios
UK health professionals may use this calculation for personalised medication dosing, particularly with medications where dosage depends on body composition rather than absolute weight. Understanding this distinction helps explain why two people of the same actual weight might receive different clinical recommendations. Our free BMI calculator can help you understand where your actual weight falls in NHS healthy weight ranges, providing context for these assessments.
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.
When Adjusted Body Weight Matters in UK Healthcare
Adjusted body weight becomes relevant in several clinical situations. It's used when prescribing certain medications where dosing accuracy is critical—particularly antibiotics, anaesthetic drugs, and some weight management medications. For individuals significantly above or below their ideal body weight, adjusted weight provides a more accurate dosing reference than absolute weight alone.
In UK weight management settings, healthcare professionals consider adjusted weight alongside other measurements like BMI, waist circumference, and body composition to create personalised plans. This is especially important when accessing prescription weight loss treatments through NHS specialist services or private prescribing, where individual health context matters. Using our free weight converter, you can easily switch between kg, stone, and pounds to understand your measurements in units you're comfortable with—helping you engage more fully with your healthcare provider's recommendations.
- 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 is adjusted body weight different from my actual weight?
Adjusted body weight is a calculated estimate that accounts for differences between your actual weight and your ideal healthy weight range, using a mathematical formula. Your actual weight is simply what the scales show. Adjusted weight is used by healthcare professionals for clinical purposes like medication dosing, while your actual weight is the starting point for BMI and other health assessments.
Why do UK healthcare professionals use adjusted body weight?
The NHS and UK private healthcare use adjusted body weight for medication dosing when accuracy is critical. It prevents over- or under-dosing in patients who are significantly above or below their ideal weight. This is particularly important with medications where dose depends on body composition rather than total body weight, ensuring safe and effective treatment tailored to your individual health profile.
Can I calculate my adjusted body weight myself?
Yes. Use the formula: Adjusted Body Weight = Ideal Body Weight + (Actual Body Weight − Ideal Body Weight) × 0.4. First, calculate your ideal weight using the Devine or Robinson formula (your GP can help). Then apply the adjustment. However, healthcare professionals should interpret adjusted weight in your personal health context, so always discuss results with your prescriber.
Is adjusted body weight used for weight loss medication in the UK?
Adjusted body weight may be considered when assessing eligibility for prescription weight loss treatments like Mounjaro or Wegovy, though NHS and private prescribers primarily use your actual BMI and health conditions. Adjusted weight helps ensure accurate medication dosing once prescribed. Your prescriber will assess your individual circumstances during clinical assessment to determine appropriate dosing.
How does adjusted body weight relate to BMI?
BMI uses your actual measured weight and height to assess health risk. Adjusted body weight is a separate clinical calculation used mainly for medication dosing. While BMI categorises you into health ranges, adjusted weight refines medication safety. Both measurements are useful in UK healthcare—BMI for screening and risk assessment, adjusted weight for precise clinical interventions and treatments.
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.