While bananas are a great pre-workout snack, make sure you grab a ripe one! Unripe fruit isn't a good idea before you work out, as it could cause uncomfortable gas and bloating, Hartley says. Choose a banana that's completely free of any green at the stem. Brown spots on the skin indicate it’s in the ripe stage. At this stage the sugar content will be absorbed easily, otherwise, the unripe banana is in the starch stage and more difficult to digest.