One banana contains 15 grams of all-natural sugar and 0 grams of added sugars. These naturally occurring sugars digest slowly and provide antioxidants, unlike the refined sugars found in junk foods. However, dietitians recommend you eat bananas in moderation. Excessively eating bananas can contribute to weight gain and high blood sugar. So if, for example, you have a banana earlier in the day as a pre workout snack, you might want to eat something else before bed.