"You are what you eat", as the saying goes. In fiction, this is often taken literally, with a character eating something that causes them to transform into whatever it was they just ate, or the creature it came from (for example, a character may start growing feathers after eating a chicken egg). Can be a source of Nightmare Fuel when used in a children's show.
This trope may also apply to abilities and behaviour associated with the food source, for example, eating brains may supposedly make one more intelligent, or eating a beef patty may make them start mooing and eating grass.
Note that this differs from You Are Who You Eat, in that the latter trope is about characters who can do this with their food as an inherent ability. This trope is for when the food itself has these special properties.
A newly-transformed sentient pile of food will often discover that it tastes delicious . See also: Cereal-Induced Superpowers. A Sister Trope of May Contain Evil. Can occur because of Tampering with Food and Drink.
- Tamaki Amajiki/Suneater from My Hero Academia has a superpower kwnow as "Reappearance", which allows him to change parts of his body into the body parts of things that he eats. His power also works as a form of Power Copying: if he eat part of his oponent's body, he will gain their superpowers.
- Wapol from One Piece can do this thanks to eating the Munch-Munch Fruit (Baku Baku no Mi).
- The Smurfs comic book story "Salad Smurfs" had the Smurfs turning into Anthropomorphic Food from eating magically-treated giant vegetables.
- Tharg's Future Shocks: In one comic set in the future humans hunt down ugly-looking snot aliens who mysteriously reproduce en masse by eating their eggs. Which naturally turns out to be the very thing that turns others into new aliens.
- The titular monster in John Carpenter's The Thing (1982) is like a virus, it can infect people by merely touching them. Since small particles are enough to take over a body, one of the scientists suggests that everyone prepare their own food and eat out of cans in order to prevent contamination via the digestive system.
- In "Royal Jelly", a short story by Roald Dahl, the eponymous substance slowly transforms a baby into a Queen bee larva. Did wonders for her dad, too.
- In Stephen King's short story "Grey Matter", a can of contaminated beer turns a man into a Blob Monster.
- In a roundabout way this happens in Dr. Franklin's Island. Semi, at that point a small manta ray-like creature, is presented with the chance to become human again. To that end powder is poured into her pool, and she notes that consuming it is just like consuming plankton - like breathing, basically. She and Miranda speculate that the powder is dried up human DNA.
- Doctor Who:
- In the serial "Delta and the Bannermen" a character called Billy intentionally eats some "royal jelly" so he can turn into an alien to be with the Cute Alien Girl he has fallen in love with and repopulate her race with her. And they lived Happily Ever After.
- In "Planet of the Ood", Ood Sigma slowly turns Halpen into an Ood by spiking his hair tonic.
- In That's So Raven Chelsea accidentally ate a hamburger on Halloween. It starts a chain of events that results in her and Raven turning themselves into cows.
- A recurring sketch in Tittybangbang featured a family obsessed with eating nothing but duck and chips. In one sketch the dad has eaten so much of it that he lays a duck's egg and a baby duck hatches. He's undeterred, and resolves to eat more duck and chips so he can provide a constant supply of duck for his family.
- A character in Chrono Cross ("Funguy") eats a special mushroom that transforms him into a half-human, half-mushroom person.
- Some raw meat chunks in Dungeon Crawl can cause a random mutation if eaten. They are thankfully labeled as such and prompt a warning if you try to eat it.
- Monster meat in the Shiren the Wanderer series transforms you into the monster the meat came from, giving you all of the powers of the original monster. You can also use the meat on enemies by throwing it at them; this can be exploited by throwing meat from The Goomba. Of course, monsters don't drop this meat normally; you have to kill them with Bufu's Staff, or better, Bufu's Cleaver, neither of which are easy to get.
- Corruption of Champions has this as a major game mechanic. Various items and potions can bestow transformations on you, slowly turning you into animal or monstrous forms representative of their origin. "Canine Peppers", for example, subtly alter your physiology into a more... canine form, while "Whisker Fruit" makes you more catlike. Items of opposed species will soon cancel out each other's transformations- and overdosing on certain transformation items will turn you permanently into that animal, resulting in a bad ending for you.
- The SaGa series has edible monster meat. In some games it can turn any character into a monster (opposed by cybernetics/robotic upgrades), and in all titles it allows monsters to grow more powerful and/or become a different type of monster.
- In Alienators: Evolution Continues, Wayne ended up spending the series mutating into a new form Once per Episode after accidentally eating one of the alien cells in the first episode.
- In an episode of The Powerpuff Girls, a boy transforms into a giant glue moster after eating radioactive glue.
- In the Courage the Cowardly Dog pilot "The Chicken From Outer Space", eating alien eggs causes Eustace to transform into a monstrous chicken man.
- The Magic School Bus showed a Real Life example with carrots. Arnold ate nothing but carrot-based snacks for days and turned orange.
- When Silkie, the Teen Titans' Team Pet was introduced, he ate some of Starfire's alien zorkaberries, which promptly turned him into an unstoppable (though still cuddly) behemoth.
- An episode of The Adventures of Jimmy Neutron: Boy Genius has Jimmy, Sheen and Carl venture into the Bahama Quadrangle and meet with a mysterious scientist named Dr. Moist. There, they find that he lures people there to feed them a mutagenic seaweed that turns them into seaweed monsters, and only a special antidote that he drinks with his weed can reverse the effects.
- In "The Terrifying Tales of Recess" (during the segment "Children of the Cornchip"), Cornchip Girl eats from a bag of "Ye Olde Crisps", an untested brand of corn chips imported from a spooky English town, which cause her to turn into a werewolf-like "monster".
- Some opposers of GMO food fear this is true whenever food includes "mutations" (or even "DNA"). Mutations happen spontaneously in all living organisms, allowing for such things as natural evolution. There could be a infinitisimally small chance that not all the vectors used for transgenic modification were integrated into the nuclei of the GMO, but the stomach produces enzymes that break down DNA.
- Eating too many carrots, or anything else with beta-carotene, can cause your body to dump the pigment into your skin cells rather than metabolise it into Vitamin A (which is seriously poisonous in excessive amounts), making you carrot-coloured. Drinkers of Sunny Delight have also suffered this.