Sugar . A medium - sized banana has about 105 grams and only 0.5 grams of fat . Bananas do contain 10 grams of protein , but that comes with a healthy dose of calcium . Bananas also offer potassium , magnesium and vitamin C .
A medium - sized banana has about 105 grams and only 0.5 grams of fat . Bananas do contain 10 grams of protein , but that comes with a healthy dose of calcium . Bananas also offer potassium , magnesium and vitamin C .