Actually, you CAN have popcorn -- no oil, butter or salt though! 3 cups of popped a day.
Here's how you make it if you don't have an air popper:
put 1/2 cup of kernals in a brown paper bag. Set in microwave on 2 minutes (more or less depending on microwave so listen for the kernals to begin to slow!) and enjoy!
I put hot sauce on mine