Unfortunately, bananas can’t be considered keto friendly. The energy provided by bananas mainly comes from carbohydrates, and most of this is sugar. The keto diet involves dramatically cutting back on carbs, which allows your body to use fat, as opposed to carbs/sugar, as it’s primary source of energy. This is known as ketosis.
Bananas are not keto-friendly. One medium banana has 21 net grams of carbohydrates and is simply too high in carbs to be part of a Ketogenic Diet. While you could eat one banana a day and stay keto by making sure that all your other food is pure fat or pure protein, that’s not very feasible. Best to leave the bananas off your ketogenic menu.
In the initial phase of a keto diet, where the goal is to maintain a state of ketosis, high-carb fruits will not be on your meal plan. However, this highly restrictive phase is temporary, and as more carbohydrates are added to your diet in later phases, banana in small amounts may be included.
On a keto diet, you need to eat fewer than 50 grams of carbs a day to keep your body in fat-burning mode. With 27 grams of carbohydrates, 14 grams of sugar, and only three grams of fiber, bananas are likely to spike your blood sugar levels and kick you out of ketosis. As such, they don’t fit too well into a keto or low-carb diet.