can I bring a box or 2 of fiber 1 bars from atlanta to barcelona

Should be no problem. I have traveled with bags and bags of energy bars, fiber bars, raisins and other snacks and had no problems. My husband travels overseas several times a year and always takes one or two boxes of energy bars and has never had an issue. It is one of the ways to save money! Good luck :)

Read this link to tsa.gov. Should help you to pack - check the links on the left side for any other questions that pop up.

http://www.tsa.gov/travelers/airtravel/prohibited/permitted-prohibited-items.shtm

Any food that's processed is fine, it's only stuff that's fresh that you have to worry about. I bring Nutrigrain bars in my carry-on to snack on while on the plane. They never seem to serve the food when I'm actually hungry!

I always bring snacks for the flight and on the ground at my destination until I can get settled and find food. Protein bars and tubes of nuts are my staples. I usually don't pack the box. Instead I put them in a ziplock bag, it's easier to pack that way and the bag is still useful when it's empty.

Watch the overall weight and size of your carry-on. Trying to stuff it full may backfire and force it to be checked.