Basal metabolic rate, or BMR, is the bare minimum number of calories needed if you were to stay on the couch all day and do nothing. Your BMR decreases as you age. It also decreases in response to eating less food in an effort to lose weight. Your BMR naturally slows down later in the day. If weight loss is your goal, eat larger meals earlier in the day when your metabolism is higher. Keep in mind that the BMR formula gives you the bare minimum caloric intake; active women will require additional calories per day.
Step on a scale to determine your weight in pounds. Multiply your weight in pounds by 4.35. For example: 154 pounds x 4.35 = 669.9. Measure your weight early in the morning before eating breakfast.
Measure your height in inches using measuring tape. Multiply your height in inches by 4.7. Example: 4.7 x 66 inches = 310.2
Multiply your age in years by 4.7. Example 4.7 x 32 = 150.4
Calculate your BMR by plugging the values from height, weight and age into the BMR formula for women. BMR = 655 + (4.35 x weight in pounds) + (4.7 x height in inches) - (4.7 x age in years).
Example: 655 + (669.9) + (310.2) - (150.4)
BMR = 1,324.9 + (310.2) - (150.4)
BMR = 1484.7
The BMR for the woman in this example is 1484.7. This means that she would need to eat 1484.7 calories to keep her metabolism operating at an optimal level if sedentary all day long.
Calculating Your Total Daily Energy Expenditure
To calculate your total daily energy expenditure (TDEE), multiply your BMR by the appropriate activity factor.
Determine your activity level:
Sedentary = BMR x 1.2
Lightly active = BMR x 1.375
Moderately active = BMR x 1.55
Very active = BMR x 1.725
Extra active = BMR x 1.9
Multiply your BMR by your activity level factor.
If your BMR is 1484.7 and you're moderately active -- doing light exercise or a sports one to three days a week -- multiply your BMR by 1.55.
BMR 1487.7 x 1.55 = 2305.9
With the above BMR, you need to eat 2305.9 calories on the days you exercise to keep your body working optimally and to not lose weight.
If weight management is your goal, track your BMR and TDEE in a notebook or online.
Track the number of calories your eat each day. Use online calorie counters to help you determine this. If weight loss is your goal, eat fewer calories than needed. As you lose weight, recalculate your BMR and TDEE
Track your activity level each day. As your activity level increases or decreases over time, recalculate your TDEE and make changes to your daily caloric intake as needed.