Ask Monica: How many calories should I eat to lose weight?

Q. I'm 31 years old and 66 inches tall and weigh about 250 lbs. How many calories should I be consuming if I want to lose weight. Should I only eat 1500 calories a day?

A.  Many experts like to reduce this question into a simple mathematic equation, namely, that 3500 calories equals one pound. Therefore, cutting 500 Calories (kcal) per day will equal one pound of weight loss per week (500 Calories x 7 days = 3500 Calories, or 1 pound).  Using Nutrition Data's Daily Needs Calculator, I figure that you would need 2500 Calories per day to maintain your current weight. So, using the simple math, eating 1500 Calories a day would cut 1000 Calories, translating into 2 pounds a week.

But in the real world, it's a little more complex than that.   First of all, a 1500-Calorie diet can feel pretty restrictive and might be hard to stick to for the long term. Secondly, suddenly cutting your caloric intake by 40% is likely to shift your body into starvation mode, in which your metabolism slows to accomodate the drop in calories. That's not what you want!

A better way to create a calorie deficit is to moderately reduce your calorie intake and at the same time increase the number of calories you burn with exercise.

Let's say you reduce your caloric intake to 1800 Calories a day (a deficit of 700 per day). Then, you burn an extra 300 Calories every day through exercise.  (You can use the Daily Needs Calculator to see how many calories various exercises burn. Walking briskly 30 minutes a day and doing 20-30 minutes of strength training per week would burn an average of 300 extra Calories per day.)

You're still creating a 7000/per week Calorie deficit, which would average out to a weight loss of 2 pounds per week, but you won't be as hungry and there's less danger of an unintended down-shift in metabolism.   In fact, exercise not only burns calories but as you add lean muscle mass (particularly through strength training) you actually increase your metabolic rate. That means you burn more calories even when you're not exercising, which can incrementally increase the pace of weight loss. It will also speed the loss of inches, which can be just as important as the loss of pounds.