This may be a stupid question so I apologize in advance, but does an extremely ripe banana truly have the same amount of calories as an unripe one? Even when it is so much sweeter? This boggles my brain.
The carbohydrate in unripe bananas is in the form of a resistant starch that is not completely digested when we eat the banana (i.e., fiber). So it is possible that when you eat the unripe banana, your body actually retains fewer calories.
As the banana ripens, more of the starch converts to sugar. So nothing is added to the banana, but it the stuff it is made of turns into a different form.
The ripe banana does have a higher glycemic index, as well.