A true snack portion should be 150 to 200 calories

What many people consider a "snack" - an energy bar, part of a bag of chips, or side order at a fast-food restaurant - might just have 400 calories or more.

A true snack, says Melanie Douglass, a registered dietitian based in Salt Lake City, is about 150 to 200 calories.

Here are several of Douglass' healthful suggestions:

For more protein, also eat a serving of nuts, sliced turkey, or a low-fat yogurt with less than 20 grams of sugar in an 8-ounce serving.

- U.S. News & World Report