What Happens to Your Blood Sugar When You Eat a Banana

Bananas—though rich in vitamins and minerals, as well as fiber and antioxidants—are naturally high in sugar, which can raise blood sugar levels. But paying attention to ripeness and making certain tweaks can help prevent spikes and still enjoy the fruit.

A banana’s effect on blood sugar hinges on its fiber and sugar content—and those two things depend on how ripe the banana is.

As bananas ripen, their fructose, glucose, and total sugar content increases, which increases blood sugar levels.

Meanwhile, unripe bananas contain more fiber than ripe bananas. These levels can vary drastically: One study showed that, per 100-gram serving, unripe bananas contain 18 grams of fiber, ripe bananas contain 4-5 grams, and overripe bananas contain only 2 grams.

The fiber content of fruit also influences how much that fruit increases blood sugar levels. Fruits with higher fiber tend to have a lower glycemic index (GI). Low-GI fruits—like bananas, when they are unripe or slightly ripe—don’t spike blood glucose levels as much as high-GI fruits do.

Here’s what you can expect from one 115-gram ripe or slightly ripe banana:

Calories: 113Fat: 0.3 grams (g)Protein: 0.9 gCarbohydrates: 26.4 gFiber: 2 gSugar: 18.2 g

People with diabetes can eat fruit, including bananas. Fruits contain sugar but also provide vitamins, minerals, and antioxidant compounds. Bananas are also a good source of fiber, which may help blunt their effects on blood sugar.

High fiber intake can also improve insulin and hA1c (a blood sugar marker) levels in people with diabetes. It is also linked to a lower risk of type 2 diabetes and its complications.

People with diabetes may want to choose smaller, less ripe bananas, and stick to one per sitting. They can also pair fruits with a source of protein or fat, such as nuts or plain yogurt, to reduce the glucose spike.

How many bananas you can eat (and how often you eat them) depends on your individual caloric and nutritional needs, and whether you’re monitoring your blood sugar levels.

If you are looking to reduce your chances of a blood sugar spike after eating a banana, here’s how to do it:

Eat your banana with some protein and fat. Consumer fruits with a balanced meal can help support blood sugar management.Choose unripe or slightly unripe bananas. Ripe and overripe bananas contain more sugar and less fiber than unripe or slightly unripe bananas.Be mindful of portion size. Eating a large banana (or multiple bananas) will increase your blood sugar levels more than eating a smaller banana.