Calorie intake is the delicate game of balance dieters play while trying to eat enough to be healthy and satisfied, while not eating so much as to gain more weight. We know that proper calorie intake is mandatory to sustain life, but how many are enough, and when does the threshold cross into 'too many?'

Determining your optimal calorie intake requires simple math and a basic understanding of what calories are and how they are used.

Your body needs a certain number of calories just to function. Without a base of 1200 calories, your body weakens and organs begin to shut down. In addition to this base, calories are needed to sustain your current weight, which could vary depending on your metabolism, activity level, and size. This total number is your maintenance number, or the number of calories required just to stay where you are.

There are several ways to approximate the number of calories you would need just to maintain your current weight. One simple method is to multiply your current weight in pounds by 15 calories. (Use 33 for kilograms.) Using this method, a 160-pound (72.3 kg) adult would need about 2400 calories to maintain his or her weight. This doesn't take into account exercise, age, gender, or special body chemistry, and is not an accurate estimate for people who have a severe percentage of body fat.

Another way to estimate your maintenance calories is the Harris-Benedict formula which considers height, weight, gender, and age.

Women = 655 + (9.6 X weight in kg.) + (1.8 X height in cm.) - (4.7 X age in years)
Women = 655 + (4.36 X weight in lbs.) + (4.57 X height in in.) - (4.7 X age in years)

Men = 66 + (13.7 X weight in kg.) + (5 X height in cm.) - (6.8 X age in years)
Men = 66 + (6.23 X weight in lbs.) + (12.7 X height in in.) - (6.8 X age in years)

Using this example, a 30-year-old, 160-pound (72.3 kg), 66-inch (168 cm.) female would require just over 1500 calories per day to maintain her body weight - a far cry from the 2400 recommended in the first method! A 35-year-old, 220-pound (100 kilogram), 74-inch (188 cm.) male would require about 2140 calories per day.

If you are trying to lose weight, you will need to subtract calories based on your expected loss rate. In order to lose one pound, you must create an approximate 3500 calorie deficit, either through exercise or a reduction in intake. Doctors recommend losing no more than one or two pounds per week, since just one pound per week will require a 500 per-day calorie reduction. To lose one pound in each week, you can create this deficit by eating 200 fewer calories and engaging in a 300 calorie loss exercise routine, or another relative combination.

To gain weight, or offset exercise and maintain your weight, add calories based on the number of calories you are burning off each day, or the number of calories needed each day to meet your weight gain requirements.

As with any exercise program, contact your doctor or nutritionist with specific dietary questions, or if you are planning to being a drastic weight-loss or gain routine. Also remember that the type of calories you consume, illnesses or conditions, and your muscle mass, will affect your weight loss or gain.

Learn more about this author, Kimberly Dawn Wells.
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