"If, for example, you have two items that are equal in sugar, fat, and calories, sometimes you'll find that one contains vitamins, minerals, and fiber while the other doesn't," says Marjorie Livingston, a professor of nutrition at the Culinary Institute of America in New York.
Opting for the more nutrient-dense snack will help ensure it has some redeeming value, even if some of the other ingredients are not top nutritional choices.
In addition, Livingston says, keep an eye on the sugar content. Some snacks, even seemingly healthy ones like flavored yogurt, are way over the top when it comes to added sweeteners.
"The American Medical Association says that when our sugar intake exceeds 25% of our total caloric intake, it impacts us nutritionally," says Livingston. "But the World Health Organization sets the threshold at 10% -- so sugar is an issue to consider."
A quick way to tell if a snack has gone over the line: It's over 250 calories a serving, it's probably got too many empty calories, Livingston says.
3. Portion, Portion, Portion
While it's OK to give kids some leeway on choosing what snacks to have, experts say it's still vital to pay attention to portion size.
"Parents should not ignore portion control boundaries just because it's a snack," says New York nutritionist Joy Bauer, MS, RD, CDN, director of JoyBauerNutrition.com. "Yes, you can relax a little in terms of allowing certain foods, but you should pay attention to how much of these foods your child is eating,"
It's also important to look for snacks with low levels of fat, saturated fat, and trans fat. Even if the package says a snack has no trans fats, read the ingredient list to be sure.
"If you see the word 'hydrogenated,' it means it has some trans fat, so avoid that snack," Bauer tells WebMD.
If your child is battling a weight problem, paying attention to portion size and total calories is vital, Bauer says. But, she says, don't deny the child the opportunity to snack.
"You don't want to exclude an overweight child from having snacks, but you must remember to include their snack calories as part of their daily caloric intake -- and teach your child how to do that as well," says Bauer.