That said, Nabisco's 100-Calorie Packs do contain less fat and sugar than regular cookies and crackers, and their taste will certainly satisfy your salt or sweet tooth -- and probably your craving.

Of course, you can easily prepare your own 100-calorie snacks, built around foods you like to eat. The key to controlling calories is to work with a reliable calorie-counting guide, then weigh and measure every ingredient -- at least at first.

"If you are not measuring, you will underestimate the portion; that's almost a guarantee," says Heller. She also recommends you study how the snack looks on the plate before you take the first bite, to get an idea of what a portion should look like.

When you're buying a snack on the run at a restaurant, deli, or street vendor, use your hands and fingers to estimate how much you're eating.

"The palm of the hand is usually a 3-ounce serving; a tablespoon is about the size of the last digit on your thumb; and if it's a long item, like string cheese, an ounce is about the length of your forefinger," says Wilson.

"Most restaurant portions are two to three times what a true single-serving portion is, particularly if you are buying a sweet treat, so keep that in mind when ordering," Wilson tells WebMD. One temptation it's usually best to avoid, she says, is buying snacks from a vending machine.

"Unless that machine is stocking fruit, I can guarantee it's almost always going to be over 100 calories -- and probably not very healthy," says Wilson.

100 Calorie Snacks: 20 Choices

Need some ideas? To get you started on the road to calorie-controlled snacking, our experts offer some suggestions for healthy 100-calorie munchies:

1. Half an apple with 2 teaspoons of peanut butter
2. An orange and a few dry-roasted nuts
3. 10 cashew nuts
4. 10 almonds
5. 2 ounces of lean roast beef
6. Half a small avocado
7. 3 ounces cooked whole-grain noodles with 1 fresh tomato and 1/2 ounce hard cheese
8. 1 seven-grain Belgian waffle
9. 4 mini rice cakes with 2 tablespoons low-fat cottage cheese
10. 3 ounces low-fat cottage cheese and 3 whole-wheat crackers
11. 1/4 cup fat-free ranch dressing with mixed raw veggies
12. 6 Wheat Thins crackers with two teaspoons of peanut butter (or any nut butter)
13. 1 small baked potato with 1/2 cup salsa and 2 tablespoons of fat-free sour cream
14. 1/3 cup of unsweetened applesauce with 1 slice of whole-wheat toast, cut into 4 strips for dunking
15. 1/2 cup frozen orange juice, eaten as sorbet
16. 2 large graham cracker squares with 1 teaspoon peanut butter
17. 3 handfuls of unbuttered popcorn, seasoned with herbs
18. 4-6 ounces of no-fat or low-fat yogurt
19. A 5-ounce tossed salad with lettuce, tomato, cucumber and 1/4 cup fat-free dressing
20. Half a "finger" of string cheese with 4 whole-wheat crackers

Originally published Sept. 23, 2004.
Medically updated Aug. 24, 2005.

SOURCES: American Journal of Clinical Nutrition 2004; 79:537-43; American Journal of Clinical Nutrition 2004; 79:774-9. Noralyn Wilson, MS, RD, spokeswoman, American Dietetic Association, Baltimore. Christine Gerbstadt, MD, RD, spokeswoman, American Dietetic Association, Altoona, Pa. Elaine Magee, MS, RD, WebMD Weight Loss Clinic dietitian; author, The Change of Life Diet and Cookbook. Samantha Heller, MS, RD, New York University Medical Center, New York.

©2005 WebMD Inc. All rights reserved.