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 Calculation — What Your Basal Metabolic Rate Means
Your basal metabolic rate (BMR) is the number of calories your body burns at rest to maintain basic functions like breathing, circulation, and cell production. Understanding your BMR is useful for weight management planning, as it shows your baseline energy expenditure before accounting for daily activity. This UK health guide explains how BMR is calculated, what it means for your weight, and how it fits into broader healthy weight management. Knowing your BMR can help you set realistic dietary targets and understand your individual metabolism.
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 to Calculate Your BMR — The Two Main Formulas
Two widely used formulas calculate BMR based on your weight, height, age, and sex. The Harris-Benedict equation (updated 1984) is the most common in UK health practice:
- Men: BMR = 88.362 + (13.397 × weight in kg) + (4.799 × height in cm) − (5.677 × age)
- Women: BMR = 447.593 + (9.247 × weight in kg) + (3.098 × height in cm) − (4.330 × age)
The Mifflin-St Jeor equation (1990) is slightly more accurate for modern populations:
- Men: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5
- Women: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161
Both formulas give results in calories per day. Individual results vary based on genetics, muscle mass, and metabolism. Your GP or a registered dietitian can provide personalised guidance on what your BMR means for your health.
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.
BMR vs TDEE — Why Both Matter for Weight Management
BMR is your resting metabolic rate — the calories you burn doing nothing. TDEE (Total Daily Energy Expenditure) is your BMR plus calories burned through activity. For weight management, TDEE is more practical: creating a calorie deficit relative to your TDEE (not BMR) supports gradual weight loss.
For example, if your BMR is 1,500 kcal and your TDEE is 2,200 kcal due to daily movement, a 500 kcal deficit means eating around 1,700 kcal daily for approximately 0.5 kg weight loss per week — the NHS-recommended safe rate.
Our free BMI calculator and weight converter help you understand your current weight status and healthy weight range, providing context for setting realistic calorie targets alongside your BMR.
- 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 a normal BMR for UK adults?
Normal BMR varies widely by age, sex, weight, and height. A typical adult has a BMR of 1,200–1,800 kcal per day. Men generally have higher BMR than women due to greater muscle mass. Your GP can help interpret your personal BMR in context of your individual health.
Does BMR change with weight loss?
Yes. As you lose weight, your BMR decreases because your body requires fewer calories to maintain a smaller mass. This is why weight loss can plateau — your body's calorie requirement drops. This is normal and expected. Maintaining muscle through activity helps preserve BMR during weight loss.
Can BMR be increased?
Building muscle through resistance exercise is the main way to increase BMR, since muscle tissue burns more calories at rest than fat tissue. Adequate protein intake, strength training 2–3 times weekly, and sufficient sleep support muscle maintenance. gradual weight management can reduce BMR — gradual loss (0.5–1 kg/week) helps preserve it.
How does BMR relate to weight loss medication?
Weight loss medications like Mounjaro and Wegovy work alongside your BMR by reducing appetite and supporting a calorie deficit. They don't directly change your BMR but help you consume fewer calories consistently. Sustainable results combine medication (if prescribed) with dietary changes and activity — your BMR calculation helps set realistic calorie targets.
Should I eat at or below my BMR for weight loss?
No. Eating below your BMR long-term is not sustainable and can slow metabolism. Instead, create a modest deficit below your TDEE (around 500 kcal/day for 0.5 kg/week loss). The NHS recommends this balanced approach. A registered dietitian or GP can help you set safe, personalised targets based on your BMR and activity level.
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.