Basal Metabolic Rate Calculator (BMR)

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BMR Calculator (Basal Metabolic Rate, Mifflin St Jeor Equation)

About this calculator

The are the three equations typically used by BMR calculators, of which the Mifflin-St Joer equation is considered the most accurate and it is the oneused by this calculator.

Mifflin-St Jeor Equation:For men:BMR = 10W + 6.25H – 5A + 5For women:BMR = 10W + 6.25H – 5A – 161

Revised Harris-Benedict Equation:For men:BMR = 13.397W + 4.799H – 5.677A + 88.362For women:BMR = 9.247W + 3.098H – 4.330A + 447.593

Katch-McArdle Formula:BMR = 370 + 21.6(1 – F)W

where:
W is body weight in kg
H is body height in cm
A is age
F is body fat in percentage (Click here for our Body Fat Calculator)

BMR Variables

Muscle Mass – Aerobic exercise such as running or cycling has no effect on BMR. However, anaerobic exercise, such as weight-lifting, indirectly leads to a higher BMR because it builds muscle mass, increasing resting energy consumption. The more muscle mass in the physical composition of an individual, the higher the BMR required to sustain their body at a certain level.

Age – The more elderly and limber an individual, the lower their BMR, or the lower the minimum caloric intake required to sustain the functioning of their organs at a certain level.

Genetics – Hereditary traits passed down from ancestors influence BMR.

Weather – Cold environments raise BMR because of the energy required to create a homeostatic body temperature. Likewise, too much external heat can raise BMR as the body expends energy to cool off internal organs. BMR increases approximately 7% for every increase of 1.36 degrees Fahrenheit in the body’s internal temperature.

Diet – Small, routinely dispersed meals increase BMR. On the other hand, starvation can reduce BMR by as much as 30%. Similar to a phone that goes into power-saving mode during the last 5% of its battery, a human body will make sacrifices such as energy levels, moods, upkeep of bodily physique, and brain functions in order to more efficiently utilize what little caloric energy is being used to sustain it.

Pregnancy – Ensuring the livelihood of a separate fetus internally increases BMR. This is why pregnant women tend to eat more than usual. Also, menopause can increase or decrease BMR depending on hormonal changes.

Supplements – Certain supplements or drugs raise BMR, mostly to fuel weight loss. Caffeine is a common one.

BMR Tests

Online BMR tests with rigid formulas are not the most accurate method of determining an individual’s BMR. It is better to consult a certified specialist or measure BMR through a calorimetry device. These handheld devices are available in many health and fitness clubs, doctor offices, and weight-loss clinics.

Resting Metabolic Rate

While the two are used interchangeably, there is a key difference in their definitions. Resting metabolic rate, or RMR for short, is the rate at which the body burns energy in a relaxed, but not fully inactive state. It is also sometimes defined as resting energy expenditure, or REE. BMR measurements must meet total physiological equilibrium while RMR conditions of measurement can be altered and defined by contextual limitations.

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