Food at the kitchen table only. They are allowed water in their room at bedtime.
Very little eating or drinking around the house occurs. We usually eat meals together at the table. Very occasionally DH and I might get a takeaway in after the DCs have gone to bed, but months can pass by in the interim. DH and I don't like tea or coffee anyway, so that only happens when there's guests. If I'm thirsty, I make a drink of water or cordial in the kitchen and drink it. No biscuits as a routine. Every few weeks we might have an alcoholic drink in front of the TV, the can goes to the bin after. DH sometimes has something puddingy a couple of hours after dinner, but clears it up after.
The DCs understand that the lounge is generally food free. They can get away with something quite clean like a banana as long as the peel is binned immediately in the kitchen. Something like self-service cereal out of the box on the lounge floor and they're dealing with the aftermath. They rarely do it. They just accept it as normal. We've done film night with popcorn a few times but seldom. They just never established a habit of snacking infront of the TV.
The exception for the bedrooms is on a weekend when I bring them a croissant to encourage them to get up and ready for a 9am class, and when DS1 has been sent up there to chill out following a tantrum/meltdown which is often triggered by hunger so he gets something like a banana put in with him despite his howls of protest, and it normally gets eaten a few minutes after I've scarpered.
The house is nothing like a showhome, more like a toy factory explosion, but keeping the majority of food and drink in the kitchen means that at least the clutter is clean. DS1 leaves a toddler like devestation zone of food droppings around his zone of the kitchen table, so I'd be very reluctant to let him eat a meal anywhere that's not easily wiped down within 3 metres! (Suspected dyslexia could be a factor here)
The natural consequence of the clear-up seems to be effective as a deterrent.