A medium green banana contains roughly 105 calories, the same as a ripe yellow banana of the same size. The weight of a medium banana is about 118 grams, and ripeness doesn’t meaningfully change the calorie count. What does change is how your body processes those calories, which matters more than most people expect.
Calories by Banana Size
Banana calories scale predictably with size. A small banana (about 100 grams) has around 89 calories. A medium banana (118 grams) lands at 105 calories. A large banana (roughly 136 grams) comes in near 121 calories. These numbers hold whether the banana is green, yellow, or spotted brown, because ripening changes the type of carbohydrate inside the fruit, not the total energy content.
If you’re tracking calories, the simplest approach is to weigh just the peeled fruit. The peel accounts for about 35% of a banana’s total weight, and calorie databases typically list the edible portion only.
Why Green Bananas Feel Different Than Ripe Ones
A green banana gets most of its carbohydrates from starch, specifically a type called resistant starch. As a banana ripens and turns yellow, that starch converts into simple sugars like fructose, glucose, and sucrose. By the time a banana has brown spots, nearly all of the starch has become sugar.
This is why a green banana tastes starchy and slightly chalky, while a ripe banana tastes sweet. The total carbohydrate content stays about the same. It’s the ratio of starch to sugar that shifts dramatically. A green banana is heavy on starch and low on sugar. A fully ripe banana is the reverse.
Resistant starch behaves more like fiber than like a typical carbohydrate. Your small intestine can’t break it down, so it passes into the large intestine where gut bacteria ferment it. This means your body absorbs fewer of the calories from a green banana compared to a ripe one, even though both technically contain the same amount. The difference is modest, probably in the range of 10 to 20 calories, but it’s real.
Blood Sugar and Glycemic Index
Green bananas have a glycemic index of about 30, which is considered low. Ripe yellow bananas score around 51, putting them in the low-to-moderate range. That’s a significant gap. For context, a GI under 55 is considered low, and anything under 35 is very low.
The practical takeaway: a green banana raises your blood sugar more slowly and to a lower peak than a ripe one. If you’re managing blood sugar levels or just trying to avoid an energy crash after eating, greener bananas are the better choice. The resistant starch slows digestion, which flattens out the blood sugar curve. A ripe banana delivers its sugars faster, producing a quicker spike and a quicker drop.
Satiety and Digestion
Because resistant starch acts like fiber, green bananas tend to keep you feeling full longer than ripe bananas. The slower digestion means energy trickles into your system over a longer period. Some people find green bananas cause bloating or gas, though. That’s the fermentation process in the large intestine, and it’s normal. If you’re not used to eating high-fiber or high-resistant-starch foods, starting with half a green banana and working up can help your gut adjust.
Ripe bananas are easier to digest, which is why they’re a go-to food when someone has an upset stomach. The tradeoff is that they don’t provide the same prebiotic benefits that resistant starch offers.
Green Bananas in Cooking
Green bananas are a staple in many cuisines, often boiled, fried, or used in stews. Cooking changes the texture from waxy and firm to something closer to a potato. Boiling a green banana doesn’t significantly alter its calorie count, though frying it in oil adds calories from the fat. A medium green banana fried in oil can easily jump from 105 to 180 or more calories depending on how much oil it absorbs.
Green banana flour has also gained popularity as a gluten-free, resistant-starch-rich alternative in baking. Two tablespoons of green banana flour contain roughly 50 calories and retain much of the resistant starch, though some is lost during processing and cooking at high temperatures.