BMR CALCULATOR

In 1899, Magnus-Levy coined the term Grundumsatz or 'basal metabolism'. BMR, or Basal Metabolic Rate, is all about the energy your body needs when you're at rest, like during a lazy day in bed. So, when does this information become useful? Primarily, it comes into play when you're dedicated to managing your weight. Further, it is helpful in the diagnosis of thyroid disease, diabetes and leukaemia. You can also utilise this information to calculate your metabolic rate. There are certain conditions to be met when you calculate BMR. Let us look into these and other relevant details circling BMR.

Introduction to BMR

BMR, or Basal Metabolic Rate, is the amount of energy your body needs to maintain essential functions like breathing and circulation at rest. It's measured under conditions that minimise external influences, such as temperature and physical activity. Simply, it represents the baseline energy required for your body's essential functions. Your diet needs to cover the energy demands of both BMR and additional activities, like work, social interactions, and leisure.

According to a study done by the Research Gate to calculate BMR, a minimum rate of heat production (free of the effects of any food consumption and 'extreme' physical environments) is measured under the following body conditions:

1. The subject must be fully awake and entirely in a resting position before and during measurement.

2. He or she should not eat anything before, meaning completely fast for 10-12 hours before the measurements.

3. The room temperature must be around 22-26°C to avoid any impact on heat production due to temperature regulation.

4. The person being measured should be relaxed, free from emotional stress and familiar with the equipment used to take measurements.

Methods to Calculate BMR

The methods to calculate BMR have evolved. Early equations, such as the Harris-Benedict equation and DuBois normal standards for BMR, laid the foundation. However, modern methods incorporate more accurate variables like lean body mass and specific metabolic measurements. Here are a few methods listed below used to calculate BMR;

1. Equation-Based Methods:

• Manual Calculations: Traditional equations like Harris-Benedict or Mifflin-St Jeor can be calculated manually using pen and paper.

• Online BMR Calculators: These calculators use established equations to provide quick estimates and are widely available on various health and fitness websites.

2. Physiological Measurements:

• Indirect Calorimetry: Actual tests conducted in a controlled environment, measuring oxygen consumption and carbon dioxide production.

• Doubly Labeled Water Method: Involves isotopic markers in body fluids, offering an accurate but less practical option for extended assessment.

3. Body Composition Assessments:

• Bioelectrical Impedance Analysis (BIA): Measures electrical resistance in the body to estimate body composition and, consequently, BMR.

• Dual-Energy X-ray Absorptiometry (DEXA): Provides detailed body composition data using X-rays for enhanced BMR accuracy.

• Bod Pod: Measures air displacement to assess body composition, contributing to BMR calculations.

4. Clinical Assessments: Resting Metabolic Rate (RMR) Measurement: Similar to BMR but measured under less strict conditions, making it more practical for specific settings.

BMR Variables

This section discusses the relevant information you must provide, the input given to calculate BMR accurately. Here are the variables that you must know;

• Age: BMR tends to decrease with age. As people age, muscle mass may decrease, impacting the body's rate of burning calories at rest.

• Gender: Men generally have a higher BMR than women. This is often attributed to men having more muscle mass and lower body fat percentage on average.

• Weight: Heavier (higher body weight) individuals typically have a higher BMR. Maintaining the body's functions in a larger body takes more energy.

• Height: Taller individuals may have a slightly higher BMR as more energy is required to maintain bodily functions in a larger frame.

• Body Composition: Muscle tissue burns more calories at rest than fat tissue. Therefore, a higher muscle-to-fat ratio can contribute to a higher BMR.

BMR Formulae

Here are the widely accurate formulas to calculate BMR:

1. Harris-Benedict Equation (1919):

• For Men: BMR = 88.362 + (13.397 * weight in kg) + (4.799 * height in cm) - (5.677 * age in years)

• For Women: BMR = 447.593 + (9.247 * weight in kg) + (3.098 * height in cm) - (4.330 * age in years)

2. Mifflin-St Jeor Equation (1990):

• For Men: BMR = 10 * weight in kg + 6.25 * height in cm - 5 * age in years + 5

• For Women: BMR = 10 * weight in kg + 6.25 * height in cm - 5 * age in years - 161

How to Calculate BMR Online?

Here is a step-wise guide to calculate BMR;

Step 1: Choose an online BMR calculator- Numerous online BMR calculators are available. Select a reliable website that provides a calculator based on the Mifflin-St Jeor equation, which is considered the most accurate method for estimating BMR.

Step 2: Gather your personal information- Gather the BMR variables we discussed earlier before using the calculator. This includes

• Your weight in kilograms,

• Your height in centimetres,

• Your age in years,

• Your gender.

Step 3: Calculate your BMR- Click the “Calculate” or “Submit” button to initiate the calculation. The calculator will process your information and display your estimated BMR in kilocalories per day (kcal/day).

Step 4: Interpret your BMR- Understanding your BMR can help you set realistic calorie goals for weight management or maintaining a healthy weight.

Step 5: Consider activity level and other factors- Remember that your BMR only accounts for basal metabolism, not the additional calories expended through physical activity. To determine your daily calorie needs, you'll need to consider your activity level using biological activity factors (PAFs). Other factors like muscle mass, pregnancy, and certain medical conditions can also influence your calorie needs. An Ideal weight calculator can help you determine one of the many other factors- a healthy weight range.

If you have specific concerns about your BMR or calorie needs, it's advisable to consult with a registered dietitian or healthcare professional. They can provide personalised guidance based on your circumstances and health goals.

Uses of BMR Calculator

In the early 20th century, BMR was measured mainly to identify thyroid-related conditions. The focus has shifted, and BMR measurements are primarily used to estimate overall energy needs and gain insights into energy regulation. Further, you can plan to gain or lose weight using the BMR calculator. These can be useful in diets like a simple 7 days diet plan for weight loss. Beyond weight management, the BMR calculator guides overall caloric intake. It helps individuals tune their nutrition plans, ensuring they meet energy requirements without excess or deficiency.

Athletes and fitness enthusiasts often use BMR calculators to optimise their training regimens, supporting performance goals and enhancing recovery. Moreover, healthcare professionals leverage BMR information in clinical settings, aiding in diagnosis, assessing and managing patients' nutritional needs.

BMR Calculator for Men

The average BMR for men is around 1600-1800 calories per day. However, this can vary depending on individual factors. For example, a man who is taller, heavier, or has more muscle mass will have a higher BMR than a man who is shorter, lighter, or has less muscle mass. Let us look at the standard BMR value for males according to body weight:

BMR Calculator for Women

The average BMR for women is around 1400-1500 calories per day. However, this can vary depending on individual factors. This may vary based on factors like menstrual cycles, puberty, emotional stress, lean mass, etc. Let us look at the standard BMR values for females according to body weight:

BMR Calculator to Lose Weight

Our bodies burn a certain number of calories every day, even when the body is at rest. You gain weight if you eat more than that number; if you eat less, you lose weight. This is where the BMR calculator helps you. The calculator allows you to know that number. Here's more detail on how a BMR calculator can help you lose weight:

1. Calculate your BMR: Understand how many calories your body burns daily. This is the first step before implementing any strategy for weight loss.

2. Find out how many calories you should burn to lose weight: We refer to the concept of calorie deficit: eating fewer calories than you burn in a day. This is because your body uses stored fat for energy once it's not getting enough energy from your diet.

3. Follow a healthy diet based on your calorie goal: Include plenty of fruits, vegetables, and whole grains.

4. Get regular exercise and homemade weight loss foods: Aim for at least 30 minutes of moderate-intensity exercise most days, along with healthy weight-loss foods to fuel the exercise.

BMR Calculator to Gain Weight

According to the National Library of Medicine, several studies found that factors like BMR, sleeping metabolic rate, and 24-hour energy expenditure, when adjusted for lean body mass, fat mass, age, and gender, independently predict future weight gain.

A BMR calculator can be a helpful tool to determine how many calories you need to consume each day to reach your goals. You must create a calorie surplus to gain weight, which means eating more calories than you burn.

Here's how to use a BMR calculator to gain weight:

1. Find a BMR calculator online: Many different calculators are available, so you can choose one you like.

2. Enter your BMR variables: Make sure you are entering your information correctly, as this will affect the accuracy of your BMR calculation. BMR variables include age, sex, height, and weight. Click on enter or submit.

3. Add 500-1000 calories to your BMR to gain weight: This will give you a safe and sustainable calorie goal for weight gain.

4. Follow a healthy diet based on your calorie goal: Include plenty of fruits, vegetables, and whole grains.

5. Strength training movements: Aim for at least 30 minutes of moderate-intensity exercise weekly. This includes activities like squats, pushups, pull-ups, and deadlifts.

Age-wise BMR Range for Men and Women

BMR generally decreases with age for both men and women. This is because muscle mass decreases with age, and muscle tissue is more metabolically active than fat tissue. Other factors affecting BMR include:

• Body composition: People with more muscle mass tend to have higher BMRs than those with less.

• Activity level: More active People tend to have higher BMRs than less active people.

• Genetics: Some people are born with higher BMRs than others.

Let us look at the standard age-wise BMR values for men and women according to age:

Here the BMR ranges are given in the unit of calories to help you better understand the standard requirements.

Expert Review on BMR Calculator

BMR calculators can be a helpful tool for individuals seeking to manage their weight. By providing an estimate of daily calorie expenditure, these calculators can assist in determining appropriate calorie intake for weight loss, maintenance, or gain. However, it is essential to recognise the limitations of BMR calculators and utilise them appropriately.

To effectively use BMR calculators for weight management, consider the following recommendations:

• Consult a healthcare professional: Seek guidance from a registered dietitian or healthcare provider to determine personalised calorie needs and develop a safe and sustainable weight management plan.

• Use a Daily Calorie Intake Calculator Beside: To keep track of the calories you consume, a daily calorie intake calculator is suitable and goes handy beside the BMR calculator, which determines the number of calories you burn at rest.

• Focus on healthy eating patterns: Prioritise a balanced diet of fruits, vegetables, whole grains, and lean protein sources.

• Incorporate regular exercise: Physical activity promotes overall health and supports weight management goals.

References

1. Henry, Jeya. 2015. “(PDF) Basal metabolic rate studies in humans: Measurement and

development of new equations.” ResearchGate.

https://www.researchgate.net/publication/7490153_Basal_metabolic_rate_studies_in_huma

s_Measurement_and_development_of_new_equations.

2. Verma, Natasha, and Senthil Kumar. 2023. “An evaluation of basal metabolic rate among

healthy individuals — a cross-sectional study - Bulletin of Faculty of Physical Therapy.”

Bulletin of Faculty of Physical Therapy.

https://bfpt.springeropen.com/articles/10.1186/s43161-023-00139-6