On cipro (ciprofloxacin) and flagyl for colitis, also diagnoses of mild diverticulosis. given vague dietary guidelines... how long eating brat diet? then what to eat?

I don't think anyone: really knows for sure regarding dietary guidelines for people with colonic infections. Common sense says "binding foods" which include bananas and grains/oats can only sustain you so far, before the lack of animal proteins and fats kicks in. While that is in and of itself not a bad thing in relation to weight loss, you should consider increasing your diet back to normal within 2 weeks.

Colitits: Those medications and that condition make it important to eat carefully but doesn't have to be BRAT diet ( Banans, Rice, Applesauce, Toast) just nothing greasy or spicy or hard to digest - soups, rice, pasta, crackers, yogurt, etc- avoid any fast foods