Bananas contain resistant starch, which ferments in your large intestine, creating by-products that actually block conversion of some carbohydrates into fuel, so replacing ordinary carbs with the resistant starch in bananas can boost fat burning. And banana fiber bulks up in your stomach, so you feel full for longer. The healthy way to do the banana diet makes sense and includes exercise. You can read about it here http://www.dolenutrition.com/bananadiet/bananadiet.htm