If you are on a diet, you may be confused as to the number of calories you need each day to lose weight. While recommended daily allowances give a ballpark amount that is sometimes divided into male and female categories, it is not difficult to determine that you may need and burn more calories than your 84-year-old grandmother who sits all day long. The formula used to compute caloric needs is the basal metabolic rate (BMR); it takes into account your weight, height and age as well as factors in your personal physical activity. This gives you a personalized amount of daily calories needed to maintain, lose or gain weight.
Convert your personal statistics into metric by multiplying your height in inches times 2.54 to arrive at centimeters. Take your weight times 0.454 to convert it to kilograms.
Calculate your BMR by inserting your measurements into the equation: 655 + (9.6 x weight) + (1.8 x height) – (4.7 x age)
For example, say a 35-year-old woman weighs 130 lbs. and is 63 inches tall. Multiply 130 lbs. times 0.454 to get 59 kg; 63 inches tall times 2.54 equals 160 cm.
Multiply 9.6 times 59 kg (equals 566.4) and 1.8 times 160 cm (equals 288).
Finish the equation:
655 + 566.4 + 288 – 35 (years old) = 1,474.4 calories per day, or your BMR.
Use your BMR to calculate your exact needs by deciding on the activity multiplier that best describes your lifestyle.
If you have a desk job and get very little exercise, multiply your BMR times 1.2 for a sedentary lifestyle.
If you are moderately active, multiply by 1.55.
If you are very active, such as participating in a sport six or seven days a week, multiply times 1.9.
For example, a 35-year-old woman exercises three times a week, so she is moderately active. Multiply her 1,474 calories per day times 1.55 to arrive at 2,284.7 calories needed per day.
1,474 x 1.55 = 2,284.7
Modify your personal numbers by using activity multipliers that fall between the main categories. For example, if you work at a desk but take a leisurely walk three times a week, use 1.375 as your activity multiplier; if you start an extremely physical job or start daily training for a marathon, change your multiplier to 1.9.
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