Basal Metabolic Rate (BMR) is the minimum caloric requirement to sustain life in a resting individual. It can be responsible for burning up to 70% of total calories expended

The following are a list of factors that effect your BMR.

• Genetics

  • People are born with different metabolism speed
• Gender
  • Males have more muscle mass and less body fat
  • Males average 10-15% higher BMR than females.
• Age
  • After 20yrs of age, BMR drops 2% per decade
• Weight
  • The heavier you are, the higher your BMR
  • Heavier women have 25% higher BMR than thinner women.
• Body Surface Area (BSA)
  • The greater your BSA, the higher your BMR is
• Body Fat Percentage (BF%)
  • A lower BF% means a higher BMR
• Diet
  • Starvation and/or a Low caloric intake, can reduce your BMR from about 20-30%
• Body Temperature
  • For every increase of 0.5C in internal temperature of the body, the BMR increases by about 7 percent.
  • The chemical reactions in the body actually occur more quickly at higher temperatures.
  • So a patient with a fever of 42C (about 4C above normal) would have an increase of about 50 percent in BMR.
• External Temperature
  • Prolonged exposure to colder temperatures can increase BMR to create the extra body heat needed.
• Glands
  • Thyroxin (produced by the thyroid gland) is a key BMR-regulator which speeds up the metabolic activity of the body.
  • The more thyroxin produced, the higher the BMR.
  • If too much thyroxin is produced (a condition known as thyrotoxicosis) BMR can actually double.
  • If too little thyroxin is produced (myxoedema) BMR may shrink to 30-40 percent of normal.
  • Adrenaline also increases the BMR to a lesser extent.
• Exercise
  • Building lean muscle helps to burn more calories and raise your BMR

 Here are the 3 top ways to calculate your Basal Metabolic Rate (BMR),

1. Gas Analysis through direct or indirect calorimetry
2. BMR Calculators
3. BMR Formulas

 The following is a list of the most popular formulas for figuring out your Basal Metabolic Rate (BMR).

Harris-Benedict Equation

• Created in 1919
  • Men: BMR = 66 + (13.7 X wt in kg) + (5 X ht in cm) - (6.8 X age in years)
  • Women: BMR = 655 + (9.6 X wt in kg) + (1.8 X ht in cm) - (4.7 X age in years)
    • 1 inch = 2.54 cm.
    • 1 kilogram = 2.2 lbs.

Katch-McArdle Formula

• Based on lean body mass
  • Men and Women have the same formula
  • BMR = 370 + (21.6 X lean mass in kg)
    • Lean Bodyweight In Pounds / 2.2 = Lean Bodyweight in Kilograms (kg)

MD Mifflin and ST St Jeor Equation

• Created in 1990
  • Males
    • BMR = 10 x weight (kg) + 6.25 x height (cm) - 5 x age (y) + 5
  • Females
    • BMR = 10 x weight (kg) + 6.25 x height (cm) - 5 x age (y)  - 161

Hatfield Formula

• Men’s BMR = 1 X body weight (kg) X 24
  • 1 kilogram = 2.2 lbs.
• Women’s BMR = .9 X body weight (kg) X 24
  • 1 kilogram = 2.2 lbs.