Pool
I usually don't plan my meals around Pool, just that I eat what I feel like a little ahead of playing. Trying to eat and shoot can be a real bother sometimes, especially if the food is a little greasy.
I have always used caffeine as a boost at times, especially for long playing sessions. When I was younger, I would down 3-4 Cokes in a row to get a caffeine boost. I drink lots of Coffee anyway, 2 12 cup pots in the morning, I am an old Navy man.
The only thing I would go out of my way to take before a big important tourney, is Ginseng and Ginko Biloba. I am convinced that they help with 'clarity' of the mind, which helps you get 'in the zone' much faster and for a longer period of time, Usually taken 2-3 hours before a tourney starts.
My Mom has a Ginseng tree right off of her apartment back patio. It has 'fan' shaped leaves and is very full and thick. Something you may not know is that the Ginseng tree is the oldest living tree known to man. In China, there are Ginseng trees more than 3,500 years old.
The Ginseng tree has one main trunk until it is about 100 years old, then the trunk splits in multiple trunks, becoming much larger than it was before.