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Basal Metabolic Rate What Is Your BMR? • Your BMR measures the minimum calorie requirement your body needs to stay alive in a resting state • It is the amount of calories your body would need if you were to stay in bed all day How Many Calories Is This? • About 65% of your calorie intake is responsible for just supplying your BMR • You need calories to: – Pump your heart – Breathe – Control your body temperature – And many other things Do We All Have The Same BMR? • We all have different BMR and there are many things that will affect what that rate is • Your BMR is the largest factor in determining your overall metabolic rate (how your body burns calories) • BMR ranges about 65 – 70 Calories per Hour in an average 70 kg man. How To Calculate BMR Women: 655 + (4.35 x weight in pounds) + (4.7 x height in inches) - (4.7 x age in years) Men: 66 + (6.23 x weight in pounds) + (12.7 x height in inches) - (6.8 x age in years) Whereby:- 1 kg = 2 lb 1 m = 39.36 inches Factors that influence BMR Genetics • Some people are born with slower metabolisms than others • Some people are born with faster metabolisms than others Gender • Men have a greater muscle mass and a lower body fat percentage (10-15% higher BMR than womem) • The higher your muscle mass, the higher your metabolism • Male sex hormone Age • Your BMR will reduce as you age. Due to reduced muscle size and increase in adipose tissue • After 20 years of age, your BMR drops about 2% every year Weight • The more you weigh, the higher your BMR • The BMR of an obese woman is 25% higher than a woman of an appropriate weight Body Surface Area • The greater your body surface area, the higher your BMR • Tall, thin people have higher BMRs Body Fat Percentage • The lower your body fat percentage, the higher your BMR Diet-Malnutrition • If you reduce your calorie intake suddenly, your BMR can drop by 30% • Your body wants to ensure that it is always has the calories it needs to survive, so cutting calories quickly will switch your body into a “survival” mode Body Temperature • For every 1 degree increase in your body temperature, your BMR increases by approximately 14% • Chemical reactions occur faster in your body at higher temperatures • You burn a lot more calories while you are sick or have fever External Temperature • Exposure to cold temperatures will increase your BMR • Prolonged exposure to heat will also increase your BMR Glands • Your thyroid gland (butterfly-shaped gland in your neck) is responsible for making thyroxin • The more thyroxin produced, the higher your BMR • Thyroxin increases the rates of chemical reactions in the cells. Glands • Growth hormone increases about 15% of BMR • This is due to direct stimulation of cellular metabolism Exercise • Exercise helps to build lean muscle tissue • The more lean muscle tissue, the higher your BMR • This means you will burn more calories – even when you are sleeping!