Not all prepackaged snack foods are sugar or calorie bombs, but weeding out the healthy options from the unhealthy can be a tricky business.

Snack foods are often labeled and marketed in a way that lead the public to believe the food item is a healthy choice, when this isnt always the case, said Tasha Temple , a registered dietitian at Northside Hospital Gwinnett in Lawrenceville, Georgia.

Thats why its so important to read labels and not only understand the names of ingredients, but what theyre providing (or not) nutritionally.

What to look for in nonperishable snacks

Start by paying attention to the serving size and understand that all of the information listed is in relation to that portion. Then, take note of the % daily value for each nutrient.

Anything 5% or less is considered low and anything 20% or higher is considered high, Atlanta-based registered dietitian Sarah Marjoram told HuffPost. This is an especially handy tidbit when checking out how much salt and sugar a specific snack contains.

Another good rule of thumb is a simple ingredient list, Marjoram added. Fewer ingredients typically indicates a healthier product.

As for how to distinguish between healthy and unhealthy versions of specific snack foods, heres a rundown of the criteria experts recommend as youre reading their labels in real time.

Granola bars

Look for granola bars that are between 100-200 calories, reasonably low in carbs (roughly 15 grams per bar), contain 3 grams or more of fiber (5-7 grams is ideal, Temple said) and at least 6 grams of protein.

Avoid bars that have lengthy ingredient lists the shorter the list and simpler the ingredients (whole grains, nuts, seeds, honey, maple syrup), the better.

Steer clear of bars that contain high fructose corn syrup , an ingredient thats been linked to weight gain and insulin resistance.