Is it always with bananas or a few other specific foods? If so, try cuting them out completely for a while, then if you like, reintroduce them in moderation. I used to WAY overeat on nuts and couldn't moderate my intake. I stopped eating them at all for at least a month. Then when I reintroduced them I was able to eat them in moderation.
Also, other members have reported success with digestive enzyme supplements. If your digestion is poor then you aren't getting the nutrition you should be from your food. which would explain being constantly hungry