Hi. I'm 5'8", 130 pounds and 28 years old. My BMI is supposedly 20. How many calories should I limit myself to in order to lose five pounds?

Well, first of all let me say that, just based on what you told me, you don't need to lose anything. But, having some experience with this issue, I can also tell you that you probably don't want to hear that little bit of advice. Remember that what you may not like about your body probably has a lot more to do with body composition than body weight. With a lower percentage of body fat and a higher percentage of muscle, you look a heck of a lot different than you do with more body fat and less muscle, even at the same weight. Whatever you wind up doing about calories and diet, you'll probably like the results a lot better if you work on shaping your body with resistance exercises (weights or machines), which will not only make you look better but will also serve to make you a "better butter burner" -- that is, your metabolic rate will increase and you will burn more calories even at rest.

That said, let me reiterate what I've talked about in the last couple of columns: Calories are important, but they are not the whole picture. What you eat, the mix, the timing, your hormonal response to food and so on are all important factors in the weight-gain equation; some say, even more important than calories. Your metabolic rate is one of those factors, and that is mainly determined by how much muscle you have. Muscle is metabolically active and burns calories; fat is basically inert and doesn't need many.

Two main factors contribute to the number of calories a person burns a day:

1. The number-one, most important contributor is what's called Basal Metabolic Rate (BMR): the number of calories it takes to keep you alive. The BMR of a 130-pound woman, all things being equal, is about 1,300 calories.
2. The second-biggest contributor to calorie expenditure is activity level. Activity calories could be anywhere from 400 a day for a sedentary lifestyle, right on up to more than twice the BMR, depending on how much exercise you do.

One formula for estimating total calories is to simply take your BMR (in your case, 1,300 calories) and multiply it by a certain number, depending on how active you are. That number is as low as 1.3 for a sedentary, or very light exercise, lifestyle -- and can go all the way up to 2.2 for exceptional athletes in training for professional or world-class events. ("Moderate" would be about 1.5 or 1.6.)

So in your case, assuming you're not doing too much exercise, you're basically looking at about 1,700 or so to maintain. Decrease that by 500 for a total of 1,200 calories a day (I would NOT go beneath that without checking with someone who knows what they're doing, at least not in the beginning). That, plus increasing your activity (exercise and so forth), will put you in a deficit of more than 500 calories a day, which will have you dropping about a pound a week. Understand that all this is theoretical and that you may lose more (or even less, though I doubt it). Be patient, and don't drive yourself nuts. Everyone responds differently and you may have to experiment, but what I've given you is an excellent place to start.

Be in good health,
Jonny

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