Rapacious Guest

Creature — Halfling Citizen

Menace

Whenever one or more creatures you control deal combat damage to a player, create a Food token.

Whenever you sacrifice a Food, put a +1/+1 counter on this creature.

When this creature leaves the battlefield, target opponent loses life equal to its power.

If an effect refers to a Food, it means any Food artifact, not just a Food artifact token. For example, you can sacrifice Tough Cookie (an Artifact Creature — Food Golem) to activate Maraleaf Rider's ability (an ability with "Sacrifice a Food" in its cost).
Food is an artifact type. Even though it appears on some creatures, it's never a creature type.
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.
Whatever you do, don't eat the delicious cards.
Rapacious Guest's third ability triggers whenever you sacrifice a Food for any reason, not just to activate a Food's activated ability.
To determine the amount of life the target opponent loses from Rapacious Guest's last ability, use Rapacious Guest's power as it last existed on the battlefield, not its power in the graveyard.