To stay alive, human body keeps it functioning at rest by heart beating, lungs breathing and other organs working, using certain number of calories, which is known as Basal Metabolic Rate or BMR. BMR is also known as metabolism. BMR accounts for nearly 60 percent of total energy expenditure. Anything that causes use of more calories, increase metabolic rate or BMR. For example, illness, fear and stress can increase BMR. BMR depends on gender, age, height, weight etc. Muscles in the body are the biggest energy burner, which is why men usually have higher BMR than women. Knowing BMR helps calculate calorie need for weight maintenance or weight loss.
Calculating BMR Manually
There are number of formulas to calculate BMR. The Miffin-St. Jeor equation is one of the reliable ones in calculating calorie needs. The equation is different for men and women. Age, height and weight are necessary input to do the calculation. Weight has to be input in kilograms and height has to input in centimeters in the equation. Age has to be input in years.
The equation for men is (9.99 x weight) + (6.25 x height) – (4.92 x age) + 5= BMR.
The equation for women is (9.99 x weight) + (6.25 x height) - (4.92 x age) – 161 = BMR.
Even though the equation is reliable, it does not consider all factors such as muscle mass and genetics that affect metabolic rates.
BMR and Calorie Goal
Knowing BMR helps create calorie deficit for weight loss. A pound of body weight is equivalent to 3500 calories. Losing a pound requires reduction of 500 calories daily intake. Daily activities and thermic effect of food are among factors that matter in daily calorie needs.
Calculating calories in order to maintain current weight need BMR to be multiplied by activity factor. For an individual with office job and no exercise, activity factor is 1.2. For one to three days of exercise, activity factor is 1.375. For five days of exercise, activity factor is 1.5. For six days of exercise or involvement in sports, activity factor is 1.725. For physically demanding job or training for marathon, activity factor is 1.9.
For example, a woman has BMR of 1388. If she exercises three days a week, the calories she needs to maintain her weight is equal to 1,388 x 1.375 or 1,909. To lose a pound of weight in a week, her daily calorie intake should be 1909-500 or 1409 calories. BMR goes down as weight does. Loss of weight requires eating less to continue to drop pounds.
Knowing BMR is highly useful in controlling weight.
Last update: June 15, 2017 02:42:44 pm