If you are really committed to going clean, you would be best to not give yourself an entire cheat day. That makes it harder to break the habit of eating unhealthy, unclean foods. One treat a week would be a better option. Just make sure you don't have any unclean foods stocked in your pantry, as that's just temptation.

As far as fiber one bars, they're not clean. They're loaded with chemicals and the sugar in them outweighs the benefits of the fiber. You'd be better off making your own granola bars and adding some ground flaxseed for fiber. Just make sure all of the ingredients you add are clean.

I definitely agree with the Cascadia Farm granola bars option. My favorite is the peanut butter...they are super delicious. I save them for treats or emergency meals when I'm stuck without access to healthy food. (I keep one of those or a Luna bar in my purse all the times).

I also agree that eventually you will not even WANT to eat the non-clean stuff. It won't taste good (you will be able to taste the chemicals and additives eventually) and they will probably upset your stomach.

Don't stress over going 100% overnight, though. A gradual transition is easier and will allow you to try out various brands and foods to determine which ones you like and don't like. I struggled through quite a few things I didn't like in the beginning and learned which brands taste best and are the best value. I definitely went through a LOT of cereals before I found the 3-4 that I buy consistently, now.