The number of calories you need is calculated by activity level as well as by body size. The basic daily energy, or caloric, requirement is determined by the basal metabolic rate (BMR) - the energy needed to sustain bodily functions (keeping warm, maintaining heart activity, making new cells, and so forth) in a resting state. Caloric requirements are largely genetically determined and generally range between 1,000 and 2,000 calories a day. However, with activity you burn more calories. Exercise increases the BMR. Chronic dieting decreases metabolic rate.
One of the causes of Suzanne's weight gain was her sedentary lifestyle. She no longer had her daily swim workouts to keep herself in shape and to burn calories more efficiently. The lack of exercise had reduced the amount of calories she burned while sitting and studying. In high school her body actually used calories more efficiently all day long because of her morning workouts. While performing the same activity (studying), she now expends fewer calories than she did a year ago.
To determine the correct calorie count for your individual needs, add your basal caloric needs to the calories required to support the physical activities you are involved in. Figuring your basal caloric needs is simple. Multiply your ideal body weight by 10 as shown in the following equation:
10 x _______ IBW = _______ basal calories
Next, determine your activity level: sedentary, moderate, or strenuous. As a rule of thumb, light activity burns fewer than 200 calories per hour, moderate between 200 and 300 calories, and strenuous burns more than 350. For a sedentary lifestyle, such as Suzanne's and Eric's, in the next equation multiply the IBW by 3. For a moderate level of physical activity-light jogging, swimming, bike riding, lots of walking-multiply the IBW by 5. For strenuous physical activity for a minimum of 45 minutes a day four times a week, multiply the IBW by 10.
3, 5, or 10 x ________ IBW = ________ activity calories
Before you add the two figures, note that there's a bonus for those who exercise strenuously. We said that Suzanne's previous exercise program had helped her body burn calories more efficiently. Persons who exercise strenuously on a regular basis not only get more calories per pound of IBW; they also get to add calories for each minute of daily exercise. Running 45 minutes a day, four times a week, averages about 25 minutes of daily exercise. Women who qualify for the bonus can add 8 calories per minute of daily exercise. Men can add 10 calories per minute of daily exercise.
8 or 10 x ________ minutes of exercise = ________ training calories
Now add all the calories necessary to maintain your ideal body weight:
___________ basal calories
+__________ activity calories
+__________ training calories
=___________ total daily caloric needs
If you find that this number of calories seems high and would cause a weight gain, your metabolic rate may have decreased because of chronic dieting, frequent weight fluctuations, or fasting.