I think, the best option is eating something when you are playing. Personaly I think very important is, that you drink enought when you are playing poker.
Before the grind I use a combination of fruit and grains, such as a banana with a little granola. At this point, the carbohydrate works as a source of energy to be able to grind longer.
I love to eat before the tournament and even during the tournament it's cool. I open a couple of tournaments and on half the screen some interesting movie.
I guess everyone is different. I don't like eating DURING due to it being a distraction, but mid-game between hands (or especially during the breaks), I usually grab something small to eat or drink. Seems to be working all right for me, but again others may be different; do what works for you I suppose
If you plan to play poker for hours on end, then energy is important, mentally & physically. Drink water, eat snacks, my favourite tends to be noodles, takes minutes to make, i also nibble on nuts & fruit.
Stress can play havoc with your digestive system. If you get stressed when playing, you probably want to adjust your diet for game days. You still need to eat and hydrate.
I like to eat, drink, and do everything i need to do before, I sit on the chair because i know its going to be long hours or atleast till the breaks come but. specialy eating where i don't have to cook during breaks its best to do before playing a session.
I drink only but low amount of drinks because it is hard to play when you drink too much and then you need to go to bathroom when you are in poker match ,I know when I was drinking beer and playing offline poker with my friends I needed to go to bathroom a lot so I drink only water when I play no any kind of alcohol espacialy beer.
I used to forget to eat while playing online.
But now I make sure I have something to eat; a little bite every 3 hours or so keeps me in a better mood, I make better decisions and do not tilt as much