When eaten in moderation, eating bananas will not make a person fat. Bananas do not contain fat; however, they do have high amounts of sugar, which is broken down into glucose. If there is an excess amount of glucose that's not used as energy, it will be converted to fat.
Bananas are a great food to eat prior to a workout, as they have high amounts of sugar and carbohydrates that can help fuel a person's workout. They also contain potassium, fibers and roughly 15 percent of the recommended dose of vitamin C. More importantly, bananas don't contain any sodium, fat or cholesterol, making them a healthy fruit that will complement a person's workout.