I put soda and other caffeinated beverages. Though, really, it depends on a lot of factors. At some point or anther, I've probably had all that stuff while gaming.
Right now I don't tend to eat many actual meals while playing stuff, but that's more because of what I've been playing moreso than habits. Roughly year ago, when I was playing FFXI, I was making a point to grind Salvage while I had breakfast. Got up extra early to do it, in fact, and still wake up earlier than I did prior to that. Similarly, I often would make lunch or dinner before sitting down to play, or between events.
There were also times I got in the habit of making tea before some events. I also ended up making it to try and relax when participating in some pickup ones, because of (virtual?) social anxiety...
Single player stuff that takes more constant focus, like I've been doing more of recently? I'll probably watch some TV while eating, then get to gaming after. Sometimes I'll end up eating, while there's downtime or I'm respawning, but more often I don't do much past bite sized snacks.
I'll often get a drink though, which could well also be water, and has at some points. Most common these days is coffee. I might end up forgetting to drink half of it because of focusing on a boss...but I'll have it sitting there.
