Good Carbs
Answering the question whether bananas contain good or bad carbs depends on how ripe it is. Unripe green bananas contain high amounts of resistant starch, while the ripe yellow bananas mainly consist of naturally occurring sugars.
Resistant starch is good for your body because they are long chains of glucose that are resistant to digestion. They act like soluble fiber in the body and may promote weight loss.
Low Glycemic index
Regardless of the calories in a banana, it is considered a low glycemic index (GI) food. Any food that raises your blood sugar levels to 55 or lower is considered to have a low GI. 56 to 69 is considered medium, and 70 or above is considered high. Most foods that fall under a low index group usually contain slowly absorbed carbs. Most energy-giving foods contain simple sugars which are quickly absorbed and may cause a spike in your blood sugar levels. There are a lot of health problems associated with high GI value foods including diabetes, obesity, cardiovascular diseases, and hypertension.
Although bananas are considered a high sugar fruit, their GI value is between 42 to 62, depending on how ripe it is. Green bananas are on the lower side, while yellow ones are on the higher scale. This means that bananas have a relatively low glycemic index compared to other carbohydrates. Note that the greener it is, the lower the GI and vice versa are. Generally, the sugar in a banana is absorbed slowly into the bloodstream leading to a stable blood sugar level.
In a study carried out on patients suffering from diabetes and high cholesterol, they were asked to add 250 grams of bananas to their breakfasts for one month. Tests carried out at the end of the month revealed significant improvement in blood sugar and cholesterol levels.