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
BMR Calculator UK — What You Need to Know
Your basal metabolic rate (BMR) is the number of calories your body burns at rest, just to maintain basic functions like breathing, circulation, and cell production. Understanding your BMR is a useful starting point for weight management and nutrition planning in the UK. It helps you determine how many calories you need daily and how to structure a sustainable calorie deficit for healthy weight loss. Our free BMI calculator and weight converter above can also help you assess your current weight status alongside your BMR estimate.
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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 BMR Works and Why It Matters in the UK
Your basal metabolic rate represents the energy your body uses at complete rest — it's the calories burned before you eat, exercise, or move around. In the UK, healthcare professionals including GPs and registered dietitians use BMR calculations to help patients understand their individual calorie requirements and plan realistic weight management strategies.
Key factors that affect your BMR include:
- Age — BMR typically decreases by 2–8% per decade after age 30
- Sex — men generally have a higher BMR than women due to greater muscle mass
- Height and weight — larger bodies require more energy at rest
- Muscle mass — muscle tissue burns more calories than fat tissue, even at rest
- Genetics — some people naturally have a faster or slower metabolism
- Hormones — thyroid function, cortisol, and other hormones affect metabolic rate
Once you know your BMR, you can calculate your total daily energy expenditure (TDEE) by multiplying your BMR by an activity factor (ranging from 1.2 for sedentary to 1.9 for very active). This gives you the total calories you burn in a typical day, helping you plan weight loss or maintenance.
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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.
UK Health Guidance and Using BMR for Weight Management
The NHS recommends a sustainable weight loss rate of 0.5 to 1 kg per week, which typically requires a calorie deficit of around 500 kcal per day. Understanding your BMR and TDEE helps you create this deficit without losing muscle or experiencing extreme hunger. If you're overweight or obese according to NHS BMI guidelines, your GP can refer you to a specialist weight management service for personalised support, including advice from a registered dietitian who may use BMR calculations to set realistic calorie targets.
Use our free weight converter to check your current weight in kg, stone, and lbs, and combine it with your BMI calculation to get a full picture of your health status. For those considering weight loss medication, our GLP-1 weight loss calculator can help you estimate potential outcomes — but always discuss your personal plan with your GP first.
- 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's the difference between BMR and TDEE?
BMR (basal metabolic rate) is calories burned at complete rest. TDEE (total daily energy expenditure) includes BMR plus calories burned through activity and digestion. To calculate TDEE, multiply your BMR by your activity factor (1.2–1.9). Both are useful for weight management planning in the UK health context.
Can I use a BMR calculator to plan weight loss?
Yes. Knowing your BMR and TDEE helps you create a safe calorie deficit for weight loss. The NHS recommends losing 0.5–1 kg per week, which requires roughly a 500 kcal daily deficit. However, individual needs vary — your GP or a registered dietitian can provide personalised guidance based on your health status.
Does BMR change over time?
Yes. BMR naturally decreases with age (around 2–8% per decade after 30) and when you lose weight. Maintaining or building muscle through resistance exercise helps preserve BMR. If your BMR seems unusually low, ask your GP to check thyroid function and other hormonal factors.
Is BMR the same for everyone?
No. BMR varies widely based on age, sex, height, weight, muscle mass, genetics, and hormones. Two people of the same weight and height may have different BMRs. This is why personalised advice from a GP or dietitian is valuable rather than relying on online calculators alone.
How does BMR relate to weight management in the UK?
Understanding your BMR helps you set realistic calorie targets for weight loss or maintenance. Combined with NHS BMI guidance and a weight management plan, it supports sustainable health outcomes. If you're considering weight loss medication, your prescriber will assess your overall health picture, not just BMR alone.
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.