The number of calories required to lose weight depends on an individual's basic metabolic rate, writes Dr. Mike Roussell for Shape magazine. The BMR is the number of calories an individual needs to maintain her current weight. To lose weight, one should eat fewer calories than required by the BMR.
Shape provides the equation to figure one's BMR. BMR = 655 plus (4.35 x weight in pounds) plus (4.7 x height in inches) minus (4.7 x age in years). Factoring in activity levels gives a truer picture of calories needed per day. An individual wishing to factor in activity levels should multiply her BMR by 1.4 to 1.9, depending on the strenuousness of activity, and add that to the BMR. Based on this number, someone wishing to lose weight can calculate precisely how many calories to eat per day to lose weight. By eating fewer calories than those specified by the BMR and by exercising to burn off additional calories, it is possible to lose weight.