The number of calories you need to eat each day for sensible weight loss depends on your basal metabolic rate, or BMR, and your activity level. Your BMR is the number of calories you burn each day if you perform no exercise at all. You can calculate your BMR from a gender-specific formula that uses your height, weight and age. Your activity level allows you to predict your total calorie expenditure each day from your BMR. You must also limit your weight loss rate to a safe level.
Step 1
Measure your height in inches with a tape measure. Multiply this value by 2.54 to obtain your height in centimeters.
Assume your height is 68 inches for this example. Your height is therefore 68 x 2.54 = 173 cm.
Step 2
Weigh yourself in pounds with a scale. Divide this value by 2.2 to obtain your height in kilograms.
Assume your weight is 147 lb. for this example. You therefore weigh 147 / 2.2 = 66.8 kg.
Step 3
Calculate your BMR if you're male. The Harris-Benedict equation provides the following formula for males: (5.003 x height) + (13.75 x weight) - (6.775 x age) + 66.5.
Assume your height is 173 cm, your weight is 66.8 kg and your age is 37 years. Your BMR is (5.003 x 173) + (13.75 x 66.8) - (6.775 x 37) + 66.5 = 1,600 calories per day.
Step 4
Calculate your BMR if you're female. The Harris-Benedict equation provides the following formula for females: (1.850 x height) + (9.563 x weight) - (4.676 x age) + 655.1.
Assume your height is 173 cm, your weight is 66.8 kg and your age is 32 years. Your BMR is (1.850 x 173) + (9.563 x 66.8) - (4.676 x 32) + 655.1 = 1,464 calories per day.
Step 5
Multiply your BMR by your activity factor to obtain the total number of calories you burn each day. An activity factor of 1.2 means that you're sedentary; an activity factor of 1.375 means you engage in light exercise up to three times per week and an activity factor of 1.55 means you're moderately active. An activity factor of 1.725 means you engage in heavy exercise at least six times per week and an activity factor of 1.9 means your job is physically demanding.
Assume your BMR is 1,600 calories per day and you're moderately active. Your activity factor is 1.55, so your total calorie expenditure is 1,600 x 1.55 = 2,480 calories per day.
Step 6
Subtract your calorie deficit from your calorie expenditure rate to obtain your calorie consumption rate. The National Institutes of Health states that you should limit your weight loss to 2 lb. per week. This is equal to a calorie deficit of 7,000 calories per week, or 1,000 calories per day.
Assume your calorie expenditure rate is 2,480 calories per day and you wish to lose weight at the maximum safe rate of 2 lb. per week. Your calorie deficit is 1,000 calories per day, so you should eat 2,418 -- 1,000 = 1,480 calories per day.
Things You'll Need
- Tape measure
- Scale
- Calculator
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