How much time before cardio? I typically eat a banana about an hour before my workout. Is this too far out? Should I eat closer to the workout time?
Answer: Basically you don't -need- to provided you have adequate glycogen stores from the morning afternoon or even day before. The key is to use energy that is stored as muscle glycogen before it gets turned into fat. This is why cyclists carb load the night before, they can use the stored glycogen the next day before it becomes fat. Your body doesn't work like a car in the sense that it is constantly converting what you put into it into useable energy, it's more like a cell phone that you charge and then use. Kind of a tortured metaphor but you get my point. There are foods that can be converted to glucose (energy) really fast. Dried fruits, crackers, any simple carbs basically. Bananas are actually not great for that purpose. They're slower to digest than say, berries. They're high in potassium and magnesium though which is great for after a work out because you're low on electrolytes.
Your goal is to have energy for a work out, and if you time it right your regular meals and healthy snacks during the day are enough. I wouldn't try and fuel yourself specifically for a work out, just eat a balanced diet at all other times and eat ENOUGH while making sure to drink lots of water. It is amazing how few people just don't eat enough nor eat healthy when they do. Solves almost all energy problems. Caffeine is completely unnecessary if you eat properly.
Haven't you had a workout where you get the timing just right and you have a ton of energy though you haven't eaten in awhile? The key is to schedule your work outs in that time frame, and then you can either eat as you go (extended cardio) or eat at the end (usually better so you don't cramp.)
At the end of the day, you have to get to know your body and also see what diet makes sense to the type of fitness you do. My best work outs are just before dinner. I've had two good meals and I've been hydrating all day. Then afterwards I can eat what ever I want because my body is in dire need of protein and carbs.