Pop and eat? Alas, healthy snacker, it's not quite that simple.

1. GO LIGHT ON FATChoose the 94% fat-free variety. It has about half the fat of the "light" variety—about 2g per 6 cups, a reasonable serving.

2. A BAG ISN'T A SERVINGThe common 3-ounce bag pops into 11 to 15 cups. Share, and eat half: about 175 calories.

3. ALONE? GO MINIMini-bags pop into about 6 cups, double the USDA serving, but that's OK. A bag of 94% fat-free has just 100 calories.

4. WATCH THE SODIUMCheck labels: It can vary from 30mg per cup to 100mg per cup. Opt for bags with 40mg or less.

5. ...OR HAUL OUT THE AIR POPPERIt adds no salt or fat. One tablespoon of kernels yields 2 to 3 cups, with just 30 calories per cup.Want to avoid the bag and pop your own kernels? Read our DIY Popcorn Guide.