One cup of air-popped popcorn is 31 calories. This is measured after popping, of course.
You can get answers to calorie questions at www.fitday.com and it's free.
Google is a good resource too.
I usually buy the light 100 calorie popcorn bags- those are a good snack.
I mean the popcorns with cheese and stuff aren't exactly low fat/low cal- those are the ones I'd stay away from as well at theater popcorn, they put a TON of oil in them.
People normally say it is bad for you because they think of it dripping with butter and salt. It is actually a great low cal fiber filled snack if you skip the butter. I am weird, I sprinkle a little time juice on my popcorn and it makes it taste delicious. I wouldn't recomment this unless you really love lime juice like me!
My favorite topping for air popped popcorn is Splenda and sea salt. Love the salty/sweet thing, and the taste is very similar to Kettle Corn, which I love!
I always eat air popped popcorn, usually 3-4 times a week. Its low calorie that way, the only thing I add is a little bit of salt free seasoning blend and some I cant believe its not butter spray, shake it up in a bag so it all gets some flavor and eat it up. Keeps me feeling full, its my go to late night snack so i dont wake up in the middle of the night with hunger.
I agree that popcorn can be an amazing filling natural snack. I am vowing to explore the more natural methods like popping in a paper bag in the microwave. For now, the 100 calories bags accompanied by some grape tomatoes, and some sweet/hot mustard (homemade with mustard powder, vinegar, Splenda) take me through some major snacky snacky times. If I add some thin sliced cheese from the deli (I get super thin sliced so a little goes a long way in terms of flavor) eaten alongside it is a mini-meal and really tops me up and keeps me out of trouble.
I think the jury is still out on whether microwave popcorn is good for you (not so sure about the chemicals), but air popped is definitely a good high fiber low cal snack!
I also love lime juice on my popcorn with salt and ground cumin. It's yummy.