Well this all depends on the type of workout. your requirements and their amounts will drastically be different considering the activity ahead. Take for instance running vs weights. Also take this into consideration...what are your trying to train your body to do? Does your body require short bursts of energy like in a crossfit type workout or are you needing longer sustained energy release for things like a long bike ride?
When it comes to gearing up for workout, carbs are your gym BFF. The key is to have a mixed bag of complex and simple ones so that the release of energy during your workout is slow and steady throughout your routine. Whole-wheat toast with fruit gives you both types of carbs with the bonus of being super easy to digest. Complex carbs will keep your motor humming, while the fruit adds an extra kick of energy. For those training for a race, bananas are perfect in raising potassium levels, which drop when you sweat a lot. For an added bonus, add a dash of cinnamon. The spice has been linked to stabilizing blood sugar and improving brain function.