Carbs in Bananas - Glycemic Index and Load

Nutritional Information, Glycemic Index and Load, Carbohydrate Info

Did you know that it is a myth that bananas should always be kept at room temperature? The banana industry has been trying unsuccessfully to correct this misinformation for years. Although banana skins will turn black in the refrigerator, the fruit will spoil less quickly if it's refrigerated. On the other hand, bananas have quite a bit of sugar, so low-carb dieters will probably not want to eat them very often, or at least in very measured amounts.

Note that what is called a medium banana is not very big -- most bananas in the store are much larger.

Carbohydrate and Fiber Counts for Bananas

  • ½ cup sliced bananas: 15 grams effective (net) carbohydrate plus 2 grams fiber and 67 calories.
  • 1 medium banana (7 inches to 7¾ inches long): 24 grams effective (net) carbohydrate plus 3 grams fiber and 105 calories.
  • 1 large banana (8 inches to 8 and 7/8 inches long): 28 grams effective carbohydrate plus 3.5 grams fiber and 121 calories.
  • 1 extra-large banana (9 inches or longer): 31 grams effective carbohydrate, plus 4 grams fiber and 135 calories.

Glycemic Index for Bananas

The glycemic index (GI) of bananas varies depending on how ripe the bananas are. This is because a lot of the carbohydrate in green bananas is in the form of a kind of resistant starch which we lack the enzyme to digest. As the fruit ripens, the starch is converted into readily available sugars.

One study of "under-ripe" bananas came up with a glycemic index of 30. One of "slightly under-ripe bananas" that were "yellow with green sections" produced a GI of 42, while another of "over-ripe" bananas was 52. However, most studies of bananas haven't specified the ripeness and have come up with GIs ranging from 46 to 70.

An average of 52 is usually assigned to bananas.

More Information about the Glycemic Index

Glycemic Load of Bananas

  • ½ cup of sliced banana: 6
  • banana (7 inches to 7¾ inches long): 10

More Information about the Glycemic Load

Health Benefits of Bananas

Bananas are a very good source of vitamin B6 and a good source of vitamin C, potassium, and manganese. Since resistant starch has been shown to contribute to healthy bacteria in our colons, green bananas could have health benefits along those lines.

More Information About Bananas at Calorie Count Plus.​

Low-Carb Banana Recipe

More Carb Profiles:


Leroux, MarcusFoster-Powell, Kaye, Holt, Susanna and Brand-Miller, Janette. "International table of glycemic index and glycemic load values: 2002." American Journal of Clinical Nutrition. Vol. 76, No. 1, 5-56, (2002).

USDA National Nutrient Database for Standard Reference, Release 28.

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