Lord, if that's true I'm a garbage can.
"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 is often given some sort of Hand Wave in that the food was genetically modified, exposed to radiation, infected with The Virus, of alien origins, past its use-by date, or some combination of the above.
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.
- The Smurfs: "Salad Smurfs" has the Smurfs turning into Anthropomorphic Food after 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 in order to eat their eggs... which naturally turns out to be the very thing that turns others into new aliens.
- Invader Zim (Oni): In one issue, Dib's investigation of mutant animals leads him to a stock of discarded, radioactive ice cream.
- Animal Crackers (2017) is based around a magic box of animal crackers owned by a circus that allows the performers to take on animal forms for their performances when eating a corresponding animal cracker (such as becoming a lion after eating a lion cracker, a gorilla after eating a gorilla cracker, etc.). A cracker shaped like the person's normal self automatically appears in the box whenever a person eats an animal cracker so they can return to normal afterward. If the human cracker in question is stolen, destroyed, or is otherwise lost, however, they're chuck out of luck; the box only gives the person the one chance to return to normal. Eating multiple crackers at once is also established to result in Mix-and-Match Critters. At the end, the protagonist is inspired by the whole adventure to turn his failed formula for dog treats into animal crackers that temporarily alter your skin to match animal coats.
- The titular monster in The Thing (1982) is like a virus, able to 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.
- The Stuff has the titular Stuff. It's incredibly addictive, and as a person eats more of it they're driven to seek out and consume increasing amounts. Eventually, the consumer melts down from the inside out into more Stuff.
- 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.
- Night Shift: In "Grey Matter", a can of contaminated beer turns a man into a Blob Monster.
- This happens in a roundabout way 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.
- Downplayed in Chocolate Fever, about a boy who eats nothing but chocolate and chocolate-covered food until he gets chocolate freckles all over his body.
- Doctor Who:
- In "Delta and the Bannermen", Billy intentionally eats some "royal jelly" so that he can turn into an alien in order to be with the Green-Skinned Space Babe who he has fallen in love with and repopulate her race with her. They live Happily Ever After.
- In "Planet of the Ood", Ood Sigma slowly turns Corrupt Corporate Executive Halpen into an Ood by serving him Ood graft instead of what Halpen thinks is hair tonic.
- In That's So Raven, Chelsea accidentally eats a hamburger on Halloween, which starts a chain of events that results in her and Raven turning themselves into cows.
- A recurring sketch in Tittybangbang features 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.
- Bill Cosby named a book I Am What I Ate... and I'm Frightened!!!
- Ancient Domains of Mystery has monster corpses provide special abilities (e.g. fire beetle for fire resistance.)
- The titular creatures from Bugsnax combine this with Anthropomorphic Food, as they're described as "half bug, half snak", and anyone who eats them has a random body part resemble a part of the Bugsnak they ate. The effects are temporary unless you eat too many. At that point, your body breaks apart and is absorbed into the massive snak gestalt that's overtaken their island, where the pieces transform into more Bugsnax.
- A character in Chrono Cross ("Funguy") eats a special mushroom that transforms him into a Mushroom Man.
- 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.
- The H-Game 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.
- SaGa (RPG) 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.
- This is the key feature of Wobbledogs; the mutation of dogs is affected by the food they have eaten. You can unlock more types of food by completing various goals.
- The entire point of We Happy Restaurant is to serve foods with mutagens and mind control materials in order to draw more customers in and of course unlock their mutation stages, along with the profit to decorate your restaurant.
- In Alienators: Evolution Continues, Wayne ends 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 (1998), a boy transforms into a giant glue monster after accidentally eating a radioactive bug that fell into his tub of glue.
- Courage the Cowardly Dog:
- In the pilot "The Chicken From Outer Space", eating alien eggs causes Eustace to transform into a monstrous chicken man.
- Another episode revolves around a giant carrot engineered by the military to make whoever eats it grow before exploding.
- The Magic School Bus shows a Real Life example with carrots. Arnold eats nothing but carrot-based snacks for days and turns orange.
- In the Team Galaxy episode "Strange Fruit", the protagonists land by mistake on an unknown alien planet, and there a hungry Josh eats one of the local fruits - despite Brett's protests that the fruit is entirely unknown and thus could be dangerous, Josh deems it safe since the local alien monkeys eat the fruits on the ground. As it turns out, the local fauna only eats the fruits after they fell from the trees - because eating a fruit straight from a branch as Josh did causes the eater to transform into a giant replica of said fruit. While at first used an Inflating Body Gag since Josh turns into a massive, orange, warts-covered pear-like-fruit, it slowly delves into the Transformation Horror territory as Josh loses the ability to move by himself, finds himself unable to speak, and starts emitting a powerful stench because he is much too ripe, aka rotting away.
- This ability is also weaponized by the protagonists when fighting off hungry fruit-eating alien monkeys, using the unripe fruits as mutagenic grenades.
- Teen Titans (2003): When Silkie is introduced, he eats some of Starfire's alien zorkaberries, which promptly turns him into an unstoppable (though still cuddly) behemoth. Subverted when it turns out that he's just molting.
- 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 Randy Cunningham: Ninth Grade Ninja, McFist industries debuts "soupsicles", bowls of soup congealed around plastic handles using an additive that Viceroy vehemently warns against consuming more than twice a day. Howard proves why after eating far more than two, and becomes highly addicted before mutating into a flabby monster hungry for more soupsicles.
- Recess: 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".
- The Simpsons:
- Referenced on a Treehouse of Horror episode in which Homer attempts to wish on a Monkey's Paw without it backfiring, and so wishes for a normal turkey sandwich. To cover all his bases, he makes sure to specify that he doesn't want the sandwich to turn him into a turkey when he eats it, among other things.
- In another episode, Bart has an Imagine Spot where he's a tester for new food products. A new soda turns him into a monster, which he finds cool.
- In one episode of American Dragon: Jake Long, Jake and his friends are baking muffins. When told to add vanilla, Spud unwittingly pours in a vial of venom extracted from a demonic scorpion (in his defense, it was right next to the vanilla container), and the resulting muffins cause the people who eat them to take on the creature's properties and begin attacking.
- SpongeBob SquarePants:
- In "Patty Hype", SpongeBob invents his own Krabby Patties that come in a multitude of colors. While initially popular with the public, a day after SpongeBob gives ownership of his stand to Mr. Krabs in exchange for the Krusty Krab, several thousand angry customers come to Mr. Krabs demanding refunds after whatever dye SpongeBob used to make the patties seeped into their skin and tongues.
- In "Best Frenemies", Mr. Krabs and Plankton team up to stop a new chain of soft drink places from putting the Krusty Krab out of business. After several failed attempts to learn the Kelpshake recipe and why it's so addictive, they finally just buy one and analyze its contents, where Karen tries to warn them of one particular ingredient but gets ignored. Soon after, they see SpongeBob covered in green fur, apparently the result of said ingredient that led to the restaurants all being shut down, and Mr. Krabs and Plankton end up equally furry not long after.
- In "The Krusty Sponge", after a less-than-glowing review of the Krusty Krab that ended with praise for SpongeBob, Mr. Krabs decides to make the Krusty Krab SpongeBob-themed. Part of this was selling Krabby Patties that had turned yellow from not being kept frozen properly as "Spongy Patties", and the people that eat them get food poisoning and turn yellow and spotted like SpongeBob himself. Unfortunately for Mr. Krabs, one of the victims of the tainted patties is a health inspector, and he ends up going to court for willfully poisoning his customers.
- In the Super Mario World episode "King Scoopa Koopa", King Koopa begins selling highly addictive egg sandwiches that eventually begin turning his customers into Chickadactyls, whom he then plans to cook and sell to dinosaurs.
- The Cuphead Show!: As a result of taking bites out of Baroness Von Bon Bon's castle and breaking the rules of her world, Cuphead and Mugman are both transformed into sweets; a gummy bear (cup?) and gingerbread man respectively. In a rare occasion of a Downer Ending for the series, they don't turn back by the end, even after escaping her clutches, and presumably get eaten alive by Elder Kettle.
- Some opponents of GMO food fear that 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 an infinitesimally 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-colored. Drinkers of Sunny Delight have also suffered this.