Finding the Correct Number of Calories to Shed Pounds
How many calories do you need to eat each day? That’s a key question if you’re trying to instill healthier habits and hold the line on weight gain.
It all comes down to numbers--calories in, calories out--and finding the right balance to maintain your weight. Tip it too much toward intake and the pounds will pile on, but tilt it the other way, even slightly, and it’s just a matter of time before unneeded pounds drop off.
The trick, of course, is figuring out how many calories are enough, which requires estimating resting metabolic rate--the number of calories required just to stay alive.
About 20% of the resting metabolic rate is accounted for by the brain and nervous system. The liver gobbles up about 32%, while the heart and lungs each take about 10% of total calories. The rest goes to the kidneys (7%) and other tissues in the body (21%.)
Resting metabolic rate varies from person to person. It declines with age but generally runs a little higher in men because of greater muscle mass, which burns more calories than does fat. That means a 160-pound man gets to eat a few more calories daily than a 160-pound woman.
Resting metabolic rate can be measured down to the calorie with sophisticated and costly medical equipment. Cheaper, hand-held devices streamline measurement and are used as marketing tools by health clubs. But for the vast majority of folks, the rate is easily estimated with a few simple calculations or by using an online calculator designed to measure resting metabolic rate (www.dallasdieti tian.com/calcalc.htm).
To do the math yourself: Take body weight in pounds and multiply by 10. Then add about 20% to 40% more calories for a sedentary lifestyle; 40% to 60% for a more-active daily life, and 60% to 80% for a highly active lifestyle. (Thus, a 120-pound moderately active person needs to eat about 1,680 calories--1,200 plus about 480 calories for activity--to maintain his or her weight, while a sedentary 150-pound person would need to consume about 1,800 calories daily--1,500 calories plus 300--to keep the bathroom scale steady.)
Even easier: Use the U.S. Dietary Guidelines, which recommend 1,600 calories a day for children, women and older adults; 2,200 a day for older children, teen girls, active women and most men and 2,800 a day for adolescent boys and active men.
Not surprisingly, weight loss is a different story and requires trimming calories below those required to maintain weight. One pound is equal to about 3,500 calories. Spread that over a week, and it works out to a deficit of about 500 calories a day--an amount that many weight-loss experts recommend achieving by cutting back on food (about 250 calories) and exercising a little more (to burn about 250 calories daily). If you do this, you’ll lose about a pound a week. Cut just 250 calories a day (125 in food, 125 in exercise) and lose approximately half a pound a week.
Or take a lesson from Thomas Wadden, director of the Weight and Eating Disorders Clinic at the University of Pennsylvania. For weight loss, he recommends eating 1,200 to 1,500 calories a day for women and 1,500 to 1,800 calories a day for men.
Of course, reducing calories almost certainly means counting them. Yet, studies show that people are notoriously bad at accurately tracking calories, a failing that gets worse with increasing body mass index. In other words, lean people “underestimate their daily calories by about 20%, while overweight people underestimate their calories by about 40%,” Wadden says.
To assign calorie totals to your food intake, there are several good sources. The University of Pennsylvania uses “The Doctor’s Pocket Calorie, Fat & Carbohydrate Counter 2002 Edition,” available in print or online at www.calorieking. com. The Interactive Healthy Eating Index, on the U.S. Department of Agriculture’s Web site at www.usda.gov/cnpp/, will calculate and save data on up to 20 days of meals. The “cyberkitchen” at www.shapeup.org will calculate food and activity; calorie counters for hand-held computers are available at www.palmblvd.com and www.healthetech.com.
You can also figure out how many calories you burn by logging on to www.caloriesperhour.com or calculating your activity level at www.shapeup.org/fitness/assess/ fset2.htm.
By keeping a close eye on your calorie intake, you’ll find you’re coming closer to a healthy diet--and lifestyle.
