To estimate your metabolic rate (how many calories you typically burn in a day at rest)…
(A) If you are a woman 18 – 30 years old, multiply your weight in pounds by 6.7; add 496 to the result.
(B) If you are a woman 31 – 60 years old, multiply your weight in pounds by four; add 829 to the result.
Then…
If you are physically active, multiply the result of (A) or (B) by 1.7.
If you are sedentary, multiply the result of (A) or (B) by 1.5.
Example, an active 28 year old woman who weighs 135 pounds can eat 2,380 calories and maintain her weight: (135 x 6.7) + 496 = 1,400 calories; 1400 x 1.7 = 2,380.
You should keep in mind that the less people eat, the lower their metabolism drops. Energy burned off decreases by one-third the amount of calories cut. For example, if you eat 1,000 calories less each day, your body’s total energy expenditure (burned) drops by about 333 calories per day. You’ve still cut out a net 700-odd calories, though. Once you start eating more calories, your metabolism reverts back to a normal rate for your new weight.
Metabolism is not forever “damaged” because of eating fewer calories for a time. The combination of eating less and being more physically active will be the cornerstones to successful weight loss and weight maintenance. We don’t expect people to go from inactivity to ninety minutes of intense exercise 5 days a week, however. Too many weight control programs that emphasize exercise err on the side of expecting too much, too soon. We recommend walking because no other form of exercise has consistently produced better results among the overweight. When you speak with those who have never been overweight, they exclaim how running, aerobics, or kick boxing has been their key to weight control. We agree, but respectfully argue that what’s worked for the physically fit may not work for the unfit.