Bananas are a rich source of carbohydrates, mainly starch in unripe bananas and sugars in ripe bananas. The carbohydrate composition of bananas changes drastically during ripening. The main component of unripe bananas is starch. Green bananas contain up to 70-80% starch, on a dry weight basis. During ripening, the starch is converted into sugars and ends up being less than 1% when the banana is fully ripe.