Food is an artifact type. Even though it appears on some creatures, it's never a creature type.

Whatever you do, don't eat the delicious cards.

In a multiplayer game, opponents who have left the game aren't counted by Gluttonous Troll's triggered ability.

You can sacrifice a Food token created by Gluttonous Troll's triggered ability to pay for the cost of its activated ability.

You can't sacrifice a Food to pay multiple costs. For example, you can't sacrifice a Food token to activate its own ability and also to activate Maraleaf Rider's ability.