drink water?

I almost always drink Coke during a chess game.
but is it good for brain concentration?
what does grandmasters or IM drink during chess.
Read somewhere that some GM drink Coke too but it might be advertisement.
I consider switching to water/coffee but after working a long day and I'm tired I feel that drinking Coke makes me a bit more ready to play chess. by Coke I mean Coca cola of course.

I think that's an orange drink? Some regional thing he likes.

Fischer had quite a crowd of apple juice bottles at his elbow in the Siegen Olympiad.

IM Rensch drinks water, lots of it.

I've seen Kramnik with a bottle of Coke during games but then again he's a total badass..

Soda is poison.

Water is poison....and doesn't taste nice

As with everything in chess. Depends on the position.

From the 28th North American Masters in Chicago.  http://www.nachess.org/index.php?option=com_content&view=article&id=93

Here are some pics from Susan Polgar of IM Rensch vs GM Friedel

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Water. Coke does not help (if it is not Diet - even then I would suggest water). If you have regular soda, the high amount of sugar causes a rise in blood sugar levels (amount of time in a normal person, I am not sure, but it does cause a spike in this level). A spike in blood sugar levels causes abnormal thinking and increased tiredness. So, go with water.

SIncerely,

A Juvenile Diabetic

Black, un creamed, un sweetened, coffee, no crash, tastes good, and heck, somewhat benifical to my health

Caffeine crashes me.  I stay away from it unless it's the last round of the day.

 Soda is not advised as it leads to a spike in blood sugar and then sugar crash. 

Coke is bad for your teeth, unless you already lost all of them?   Water is the best in my opinion, but you could lose time off the clock if you need to go?   My best advise is to take care of your needs before the game and just concentrate on your moves.

  Forgot to add, Snakes presentation was also good!  Drinks out of ones chess pieces, never though of that and it will not cause tooth decay like coke will!  Think about it, once you finish a piece it will become camouflage and it could sneak behind enemy lines.

adderral will help you concentrate

Water

no the point is you capture a piece you have to drink it, if you checkmate, you have to drink the king, never ever play Bullet in this manner.

Small amounts of caffeine are good for athletes, but I have idea if it would be good for chess. I'm pretty sure eating isn't good before a game though.

The human body is more than three quarters H2O, so it's important to get enough of it.  The warrior, it is said, should concern himself with the first three levels of breathing; the fourth level is left to the philosophers.

The reason you feel better after having Coke is mostly due to the caffine content, which studies suggest visably increases brain activity and stimulates short term memory (just what we need when playing chess!). However Soda has a big negative effect in its sugar content which raises blood sugar levels and results in a "crash effect". As someone suggested already, if you want the caffine, avoid drinks with sugar. Black coffee and teas, such as Green Tea, are probably better choices as they give you the caffine without the loaded sugar levels.

Having said that, drinking plenty of water is something I definitely recommend especially since caffine can dehydrate yourself and studies also suggest that drinking water improves brain function too. Many people drink significantly less water than they ought to on a daily basis and add to the dehydration effect with drinks such as soda's, coffees, and other caffinated beverages which leeches water from your body. Add to the stress during a chess game and such, it can only help to have a bottle (or more!) of water nearby and to drink throughout the game.

I drink lots of water during my games, and even having to use the facilities often actually isn't bad as walking helps to keep the mind more clear with increased blood flow throughout the body, especially the brain, and that gets more oxygen to the brain which is key for brain function. So drink water, have improved brain function, be healthy, and enjoy! :)

I just play on-line for about a 1 hour... 2 or 3 minutes games...

Most of the times I dont drink anything....

But i guess if I have thirst I will drink water :)

Go with water. Staying hydrated maintains the clarity of your mind. Drinking sugar temporarily wakes you up, but once the sugar rush is over, you're worse than you started. Secondly, sodas dehydrate your body (instead of recycling the liquid you take in, your kidneys decide to let an increased level of water pass through your system); thus, you'll have to deal with the mind-clouding effects of the soda. On top of that is the fact that caffeine, although a brain stimulant, has temporary effects as well. Chess is a game of concentration--crashing near the end of the game probably won't help.

On the other hand, caffeine is addictive, and coke tastes great. The compensation for drinking coke is that you might feel better. In fact, had you not read my post, you'd be influenced by the placebo effect of coke supposedly having a positive effect on your chess ability. Still, if you "believe" that drinking soda helps, it might have a minor psychological effect on your performance. Keep in mind that telling yourself that soda is good for your chess has the potential to build/amplify an addiction.

Ultimately, the choice is yours.