As we discussed last week, Basal Metabolic Rate is the number of calories it takes, basically, to keep you alive. It's the amount of calories you spend making new red blood cells, taking in air, maintaining body temperature and carrying on other basic metabolic processes.

In general, basal metabolism is the largest component of what we call "calorie burning" and what scientists call "energy expenditure." Here's a simple formula for estimating yours. (Remember, this is the theoretical number of calories you'd need to maintain your current weight, assuming that you never got out of bed in the morning. Remember also that, like every estimate, it's going to be imperfect: The more muscle you have, the higher your metabolic rate.) There are other factors to consider, so your own personal caloric needs may be higher or lower than the formula predicts, but the formula is a good place to start.

Take your current weight in pounds and convert it to kilograms (one kilogram equals 2.2 pounds, so just divide your weight in pounds by 2.2 and you'll get the number; round it off for simplicity's sake). As a woman, you'll first multiply your weight in kilograms by 0.9; then take the resulting number and multiply it by 24, and voila -- that's your estimated Basal Metabolic Rate. (Men multiply their weight in kilograms by 24 to determine their BMR estimate.)