It's the middle of the afternoon. Your stomach is grumbling, and you could swear the vending machine is humming your name. So now you're debating: chocolate bar or potato chips? Cheese crackers or mini-bag of cookies? You're leaving with something, but you don't want to derail your diet.One day soon, the decision may not be so hard: Vending machines offering healthier fare - yogurt, fruit crisps, energy bars - are sprouting up. But for now, if you find yourself in front of a machine, choose these snacks that provide nutrition, not just calories:Peanuts or almonds. They are a good source of protein and fiber, so you'll feel fuller longer. They also provide vitamins and minerals, as well as healthy fats, which may help lower cholesterol levels. The downside: Nuts are high in calories, so watch your portions.Pretzels. Compared with potato chips, they have fewer calories and less fat: 1 ounce of pretzels has 108 calories and less than 1 gram fat; chips have 154 calories and more than 10 grams fat. But pretzels lose in the sodium department, packing 385 mg an ounce vs. chips' 136 mg. Choose unsalted or whole-grain if available.Popcorn. Fat-free or reduced-fat, air-popped popcorn is the healthiest option. It adds fiber to your diet for very few calories. Even if a ready-made bag says "air-popped," check the label for total fat, saturated fat and trans fat (do the same for microwave popcorn). Oil may be added for flavor, which boosts fat.Crackers and peanut butter. The combination of fiber and complex carbohydrates in whole-wheat crackers and the protein in peanut butter will boost your energy.Dried fruit. It contains the same nutritional value as fresh fruit (with the possible exception of fiber) but may be higher in calories (1/2 cup of dried is about the same as 1 cup whole). Raisins, cranberries and apricots often are dried with little or no added sugar.- The Doctors is an Emmy-winning daytime TV show with pediatrician Jim Sears, OB-GYN Lisa Masterson, ER physician Travis Stork, and plastic surgeon Andrew Ordon. Check www.thedoctorstv.com for local listings.