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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What Is Average BMR and Why Does It Matter?
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 average BMR is essential for weight management because it forms the foundation of your daily calorie needs. The average BMR varies significantly based on age, sex, height, weight, and muscle mass. For most UK adults, BMR ranges between 1,200 and 1,800 calories per day. Knowing your personal BMR helps you understand how many calories you need to consume to maintain, lose, or gain weight sustainably.
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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 Is Calculated and What Affects It
BMR is calculated using the Harris-Benedict or Katch-McArdle formula, which takes into account your age, sex, height, weight, and body composition. The Harris-Benedict equation is the most widely used:
- Men: BMR = 88.362 + (13.397 × weight in kg) + (4.799 × height in cm) – (5.677 × age in years)
- Women: BMR = 447.593 + (9.247 × weight in kg) + (3.098 × height in cm) – (4.330 × age in years)
Several factors affect your BMR: muscle mass increases BMR because muscle tissue burns more calories at rest than fat tissue. Age is also significant — BMR naturally decreases by approximately 2% per decade after age 30. Hormones, particularly thyroid function, directly influence metabolism. Climate, genetics, and even certain medications can raise or lower your BMR. Women typically have a lower average BMR than men of similar weight because they generally have less muscle mass.
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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.
Average BMR Ranges for UK Adults
The average BMR for a sedentary UK adult woman is approximately 1,400–1,500 calories per day, whilst for men it's typically 1,600–1,800 calories per day. These are broad averages — your actual BMR depends on your individual characteristics. Once you know your BMR, your total daily energy expenditure (TDEE) is calculated by multiplying your BMR by an activity factor (typically 1.2–1.9 depending on exercise frequency). For sustainable weight loss, the NHS recommends a calorie deficit of around 500 calories per day, which typically results in losing approximately 0.5 kg per week. Use our free BMI calculator and weight converter to understand where your current weight falls on NHS health guidelines, and track changes with our progress tracker as you work towards your goals.
- 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) is your BMR multiplied by your activity level. TDEE includes exercise, daily movement, and digestion. Understanding both helps you calculate the right calorie intake for weight management.
Does BMR change with weight loss?
Yes. As you lose weight, your BMR decreases slightly because you have less body mass to maintain. This is why weight loss becomes harder over time — you may need to reduce calories further or increase activity. Preserving muscle mass through resistance exercise helps maintain a higher BMR during weight loss.
Can I increase my average BMR?
Yes, primarily through building muscle mass via strength training, which requires the most energy at rest. Adequate protein intake, good sleep, and managing stress also support metabolic health. Conversely, very restrictive diets can lower BMR, which is why gradual, sustainable calorie deficits are recommended.
How does BMR relate to weight management medications?
GLP-1 medications like Wegovy work by reducing appetite and food intake, creating a calorie deficit. They don't directly increase BMR, but weight loss achieved through these medications (typically 14–21% of body weight in clinical trials) naturally lowers your calorie requirements as your body mass decreases.
Why do men have a higher average BMR than women?
Men typically have more muscle mass and less body fat than women of similar weight. Because muscle tissue is metabolically active and burns more calories at rest, men's average BMR is approximately 5–10% higher. This difference decreases with age as both sexes experience muscle loss.
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.