Craving a salty treat at 4 p.m.? If you’re tempted to swing by the vending machine, you’re not alone: 97 percent of adults snack, and those sweet, salty, crunchy or chewy foods add nearly 600 calories to their daily diets.

That’s according to an analysis involving more than 44,000 people published last year in the Journal of Nutrition. But snacking isn’t always bad, especially if you have a small appetite and find it difficult to get all the nutrients you need.

Most adults should aim for 150 or fewer calories in a snack. It can be tough to make a good choice when you can’t see the nutrition labels in vending machines, but you won’t have to guess how many calories are in those Skittles for much longer. Under last year’s health-care overhaul law, operators of more than 20 vending machines will soon be required to post calorie counts.

And when the munchies strike:

Don’t follow your nose. Adults exposed to the sight and smell of pizza for a minute reported feeling hungrier than before, according to a June 2010 study published in the International Journal of Obesity.

(Jahi Chikwendiu/Washington Post)

Watch your portions. To avoid eating, say, an entire bag of pretzels, measure a serving size before you start snacking.

Look for better machines. Seek out more-healthful vending options, such as Del Monte’s fresh fruit and vegetable line, which includes bananas, pineapples and vegetables with a light dip.

Copyright 2011. Consumers Union of United States Inc.