What Is A Calorie? By Karen Asp

Calories: You've counted them, cut them, burned them and even cursed them. But what exactly is a calorie? Flip open a dictionary and you'll find that a calorie is defined as "the amount of heat needed to raise the temperature of one gram of water one degree Celsius." If that's mumbo jumbo to you, then here's a simpler explanation: Calories are simply a way to measure energy. Think of calories in food as fuel -- they're what keep your body going. What does that have to do with the number on the scale? Because one pound of body fat equals about 3,500 calories, you need to cut 3,500 calories from your diet to lose one pound.

Slash and Burn
Eliminating 3,500 calories sounds like a lot, but dieting alone isn't the only way to slash calories. "If you can cut some calories through your diet and expend some through physical activity, you'll have better results losing weight," says Lyssie Lakatos, R.D., C.D.N., a New York City-based nutrition expert and co-author of 'Fire Up Your Metabolism.' If you can slash 500 calories somewhere in your day, you'll lose weight, Lakatos says. Maintain your lowered calorie intake for a week, you could drop a pound. "That might sound slow, but losing one pound a week ensures a safe, healthy and long-lasting loss," she says.

It's easier than you think if you consider how small changes can add up. For example: If you're eating a tuna sandwich for lunch, switch from regular to light mayonnaise and you'll save 100 calories per two tablespoons. Go for a brisk 15-or-20 minute walk, and you'll burn another 100. Then instead of eating a cup of full-fat ice cream, cut your portion to half a cup and you could save 250 calories.

Count 'Em Up
Outside of trying to achieve a daily 500-calorie deficit, should you also be counting every calorie you eat? Not necessarily. Tracking every calorie can turn dieting into an overwhelming, unpleasant, and time-consuming task. "You'll drive yourself nuts if you try counting every calorie," Lakatos says. But you should have some idea what foods are low in calories (think fruits, vegetables, fish, baked or grilled chicken and low-fat dairy products) and what foods are high in calories so you can make healthy selections, whether you're grocery shopping or dining out.