Stick Figure #1: "Jenny! Guess what? I just lost thirty pounds in five days!"
Stick Figure #2: "Wow, holy heck, how did you do that?"
Stick Figure #1: [lifts up dress] "They call it 'The Egyptian Cleanse'."
Maybe a character doesn't like his current shape and decides he's going to drop those pesky pounds if it kills him, and they undertake a rigorous diet and exercise program. Maybe he meets a mysterious on the street who sells them a drug, potion, spell or curse with incredible slimming properties.
At first, all goes according to plan, as they lose weight (or at least takes steps to do so). And then everything goes straight downhill.
This trope is for works in which weight loss goes horribly wrong (or, even worse, horribly right). Maybe the characters lose too much weight and are in danger of disappearing altogether. Maybe they unwittingly sign themselves up for a weight-loss service with overly restrictive (read: lethal) penalties. Maybe the diet is magical and requires the sacrificing of children. Expect many examples to involve tapeworms, parasites which are known to cause this to people in real life. Really nasty examples may overlap with Body Horror, and self-inflicted magical ones might cross over with Be Careful What You Wish For.
Compare Fashion Hurts, for other ways in which the effort to maintain appearance can be painful and/or harmful, and Dead Weight and Fattening the Victim for other cases in which weight is associated with horror.
This trope appears in the following works:
- The Pet Shop of Horrors story "Diet" involves three people all coming to Count D for assistance in losing weight — a chubby teenager named Em looking to slim down before prom, a model obsessed with finding an easy way to stay slim, and a boxer looking to prepare for an upcoming match. Count D gives them each a very different "pet" to meet their requests, which results in very different endings. The teenager is given a personal trainer that manages her exercise and meals, the model is given a pearl to swallow that will magically let her eat whatever she wants, and the boxer is given a parrot that constantly suggests he take a break and have something to eat. Em reaches her goals through hard work and is happier for it. The boxer loses his match because of his dieting, but learns to enjoy a more balanced life. And the model? She collapses and a new being hatches out of her body, having finished its incubation period inside her stomach.
- Batman: Black and White has the story "Fat City." A freak accident turns a puddle of grease into a sentient monster that kills people by sucking all of the fat from their bodies. While it at first only goes after larger individuals, it eventually starts attacking anyone it can find by crawling up through plumbing. Batman is only able to defeat the monster with help from "Gotham's fattest woman" Chloe Willow, who agrees to serve as live bait for the beast and eventually pulls a Heroic Sacrifice to destroy it for good.
- Similar circumstances occur in Dead High Yearbook where a teenage girl takes an herbal supplement to lose weight but becomes skeletally thin. Eventually her body bursts into a giant tapeworm that devours the muscle-bound form of a schoolmate who suffered similarly horrific results from a muscle-building supplement.
- In an issue of the Italian horror comic Dylan Dog a demon is trying to do good, but not being familiar with the concept he keeps bungling up, with horrific consequences. For one of his "good deeds", he sends some magic diet pills to a fat girl who wishes to be thin. She loses weight near-instantly and gets the figure of a supermodel, but when she wakes up the following day she's wasted to little more than a skeleton. And that's when the flesh-eating bugs who've been "slimming her down" from the inside break through her skin and devour the rest of her.
- An old Marvel Comics horror book had a rich but fat man seeking quick ways to weight loss after his doctor informs him his health is at risk. He finds a mystic who has a potion that can help him lose weight, but he warns him it's untested. He pressures him into giving it anyway by threatening to seize the land his people are currently living on. When he takes it, he drastically loses weight and has to spend half his vast fortune constantly eating to keep from wasting away. The other half he spends desperately searching for the mystic for a cure, as he and his people have moved to parts unknown.
- In the French comic Mélusine, the eponymous witch hypnotizes an obese man into losing weight. She drops by his home a while later to see how he's doing... and finds that his wife is hiding his toolbox, he's cut off his legs and is trying to bite off his fingers while mumbling a Madness Mantra about losing weight.
- In the Vault of Horror story "Dying to Lose Weight!", a traveling doctor offers to help a town's overweight residents through use of a special pill. It works too well - those who take the pill lose weight to the point of wasting away and dying. When the doctor returns to the town six months later and is chased into the mausoleum by its angered residents, he comes face to face with the thing that had killed his victims - a giant tapeworm.
- Whoever is chosen as Famine in Apocalypse's Horsemen can cause people to become emaciated by touching them.
- The Blob's girth is entirely due to his mutation. Therefore, when he's completely depowered, he loses it all, but doesn't lose the excess skin with it. The first time he comments on how disgusting he looks, the second he attempts suicide but can't because he can't cut anything vital past all his folds.
- Garfield has had nightmares of these, such as slipping down a sewer drain or being reduced to just a skeleton. He would then proceed to gorge on lasagna to avoid letting these nightmares come true.
- The ABCs of Death: In "X is for XXL," Gertrude, an overweight woman, wanders the streets of France as people everywhere taunt her size; she is haunted by images of thin, attractive women. She sadly gorges herself on food before deciding to finally do something about her weight. Using a variety of sharp objects, Gertrude proceeds to cut the fat off of her body. She walks out of the bathtub in a skeletal state and missing all her skin; she poses briefly and then bleeds to death.
- In The Killing of a Sacred Deer, the second stage of Martin's curse on Dr. Murphy's family is the inability to eat food, which makes his affected son and daughter lose weight. Not only do they completely lack appetites, but attempting to put food in their mouths makes them instantly cough it back up. Dr. Murphy and his wife Anna are eventually forced to intubate the kids so they can get enough nutrients to live.
- Poultrygeist: Night of the Chicken Dead: Mixed with Cursed with Awesome, as Jared finds himself ecstatic over a thin version of himself ripping out of his morbidly obese body (though he does lack skin).
- In XX, the first segment, "The Box," is about a mother and son who encounter a mysterious man carrying a beautifully gift-wrapped box on the subway. The man lets the boy peek inside the box, which makes him completely lose the will to eat. Things get worse when he shares the secret of what he saw with his sister and father, who also stop eating upon hearing it. By the segment's end, they are all horrifically emaciated and eventually die offscreen.
- In "Fat Farm" by Orson Scott Card, a very rich, very fat man uses a service to copy himself into a healthy body. Unfortunately, he didn't check to see what happens to the original. Turns out it becomes the property of the cloning company... and they're not very humane with their human resources.
- Zig-zagged in the Goosebumps book Say Cheese and Die — Again!. The male protagonist and his female friend both fall victim to the evil camera, with a picture showing him as morbidly obese, and his female friend as a skeleton. He starts to gain weight involuntarily, she starts to lose it.
- In "The Iron Chancellor" by Robert Silverberg, a family purchases a Robot Maid to oversee their diet. It does its job a bit too well, so they try to adjust its programming and short something out.
- In The Monkey Treatment by George R. R. Martin, a fat guy who's tried every diet inadvertently signs up for the monkey treatment, in which an invisible magic monkey sits on his back and snatches away all his food before he can eat it. At first, this seems to work great — but then he realizes that for every pound he loses, the monkey gains one, so he's still carrying around the same weight as before. Even worse, as the monkey grows bigger, its malevolence and power over its human host increase as well, and once it's grown big enough, it begins to completely absorb its host's body into its own, effectively replacing the original person and reducing them to nothing but a shriveled, vestigial appendage.
- In My Best Friend's Exorcism, Big Beautiful Woman Margaret is obsessed with losing weight and constantly goes through fad diets. Gretchen - who is possessed by a demon - convinces her to try a new weight loss treatment that causes her to fade away to nothing and end up bed-bound and near death. When Abby visits her, she realizes that the "normal" treatment Gretchen has given Margaret is actually tapeworm eggs. She has been eating tapeworm this entire time, and it has hatched and grown inside her.
- In the novelette "The Pill" by Meg Elison, there's a new miracle pill that causes people to lose weight in a matter of days and stay thin afterwards (as long as they keep taking it). But there are two big catches. First, the initial course is incredibly painful. Second, there's a not-insignificant chance that taking it will kill you. Unfortunately, society at large decides to ignore both of these, and the pressure for everyone to take it grows and grows.
- Stephen King, unsurprisingly, has done a couple of these:
- In Thinner, a fat lawyer is cursed by a gypsy to lose weight. As in, all of it.
- In the Night Shift short story "Quitters, Inc.", a guy signs up with the eponymous firm to help him quit smoking, only to learn that their methodology is basically 'we will torture, mutilate, and ultimately kill you and your family if you keep smoking.' He manages to give up smoking with only one infraction, but he gains weight during the process. His caseworker at the firm says that he should lose the weight quickly or else they'll return to the 'mutilating your family' thing. Later he bumps into a family member of the coworker that introduced him to the firm and finds out the firm wasn't kidding about that.
- In the YA novel Elevation a man gradually loses weight over several months, though in an unusual twist he doesn't lose mass. He stays the same size, but gravity slowly stops pulling him down.
- The Troop: The monsters are tapeworms that afflict their victims with monstrous, unstoppable, and insatiable hunger and cause them to lose weight rapidly even as they're eating whatever they can get their hands on. There's also a Take That! implicit in that the experiment gone wrong is all a result of an attempt to find a new weight loss drug.
- In H. G. Wells's The Truth About Pyecraft, a very fat man takes a potion to lose weight. And he does — but he doesn't actually become thinner. He just weighs less until he's floating up into the air like a large balloon. A rare Played for Laughs example.
- The 4400: In "Weight of the World," Trent Appelbaum, a salesman who disappeared in 1989, discovers that his saliva is a catalyst for weight loss after his loan shark Dmitri Kazar lost 75 pounds within 48 hours of drinking from Trent's beer bottle. Dmitri then brings his wife Celeste to him so that she can lose weight. After she and Trent drink from the same water bottle, Celeste loses 23 pounds just as quickly. Trent sees the business potential in his ability as it could be used to wipe out obesity. Drandix Laboratories agrees to pay him $40 million for exclusive access to his ability. However, the Kazars both die of starvation. NTAC determines that there is a protein in Trent's saliva that hyper-accelerates a person's metabolism, stimulating the brain to produce epinephrine and break down fat cells. As such, exposure to the saliva caused the Kazars to burn calories faster than they could take them in, and they starved to death in spite of the fact that they were eating everything that they could get their hands on.
- Breaking Bad: In the final two episodes, Walter White has lost so much weight from his cancer that his wedding ring no longer fits on his finger.
- Doctor Who: In "Partners in Crime", Adipose Industries produces a special pill that makes your fat walk away: literally, it turns body fat into little creatures called "Adipose" that looks like anthropomorphic marshmallows, which then leaves the host's body while they're asleep. Being awake while this is going on may cause the company to convert everything into Adipose as a way of keeping a trade secret secret.
- Inside No. 9: In "Tempting Fate", Frank's wife Barbara was very overweight and felt a lot of self-consciousness and self-loathing about it. Even though Frank loved her just as she was, he wished for her to be thin so she would be happier. She ended up getting her wish...by dying of cancer, which caused her to fade away to a skeleton before dying.
- One episode of Sabrina the Teenage Witch has a crooked salesman from the Other Realm enchant Sabrina's mirror so she'll look larger and thus buy his weight-loss products. She keeps it up until her body literally fades away to nothing at a school dance.
- In the Saturday Night Live skit "Jimmy Tango's Fat Busters," Jim Carrey plays the eponymous infomercial host, whose method of losing dozens of pounds in days involves a combination of a suit of heat beads and crystal meth, the "Riding the Snake" method, and leaves all three testimonials alternately celebrating their massive weight loss and reporting extreme physical and mental (up-front but far from exclusively hallucinations) side effects. The last thing to happen is Tango challenging a customer who has come to believe he's the Devil to a psychic duel ("SCAN ME!"), which ends in the man bleeding from the forehead and passing out.
- In the Smallville episode "Craving", bullied, overweight teen Jodi takes Kryptonite-laced vegetable shakes in order to lose weight. The pounds melt off and she starts to get positive attention from her classmates. She is overjoyed until she realizes the weight loss will not stop, and she is forced to eat nonstop just to temporarily stop her hunger pangs. When regular food no longer works, she moves to freshly killed raw meat and then to sucking all the fat and marrow out of other humans, the only thing that seems to sate the hunger. It leaves one kid (a Jerk Jock who originally bullied her) in a coma, and it's heavily implied that it would kill her next victim—Pete. Thankfully, Jodi has a Heel Realization moment and stops herself with some help from Clark.
- One episode of Todd and the Book of Pure Evil sees an overweight girl use the titular Tome of Eldritch Lore to make herself instantly thinner. While it works, it also transforms the fat from her body into a sentient monster that makes all of the other girls in school become huge; this is a problem for Todd, who has a deep-rooted fear of fat women.
- Played for Drama in Red Dead Redemption II. The player is treated to gradually watching the tall, broad-shouldered and tough-as-nails cowboy Arthur Morgan gradually waste away to Nothing but Skin and Bones from tuberculosis, a bacterial infection that was commonly a death sentence for anyone who contracted it in the late 1800s. This also affects the cores that are tied to his physical health. It's actually possible for him to become more underweight than the game normally allows, and it's practically guaranteed to happen by the time of the final mission.
- A Played for Laughs example is Bob from the Tekken series, an acrofatic character who likes his overweight status. However, in his Tekken 6 ending, after all the effort to win the King of Iron Fist Tournament, he suddenly loses 150 pounds, becoming slim, which is a shock for him. Bob thinks his weight loss is a curse for him, as he also loses his strength and speed gained with the training that made him fat. First being a cameo, this later becomes a separate character in Tag Tournament 2 as "Slim Bob".
- Inverted in the Aaahh!!! Real Monsters episode "Internal Affairs" where the normally rail-thin Oblina bloats up to a gargantuan size after eating a parasite monster that makes her continuously hungry, putting her in danger of bursting and setting off the episode's "Fantastic Voyage" Plot.
- A variation—definitely Played for Laughs—occurs in The Amazing World of Gumball episode "The Diet." Richard can't seem to lose weight, so Gumball and Darwin help him exercise and eat more fruits and vegetables. He becomes more muscular as a result, but eventually, his good looks go to his head and he becomes obsessed with working out to get buffer, forcing Gumball and Darwin to stop him before he becomes too ripped and handsome to contain.
- Aqua Teen Hunger Force
- Played for Laughs during one of Dr. Weird's Cold Openings, where he triumphantly declares he's lost weight!... Manually!... With a chainsaw! Cut to (what is left of) his legs and lower body. He then declares he needs to lose another twenty pounds and goes to work again just as Steve decides he'd rather be anywhere else.
- The episode "Diet" features Carl betting Meatwad that his new diet plan, "The South Bronx Paradise Diet" — where he eats a special candy bar before every meal, then gorges himself far more than he would normally — is more effective than Meatwad cutting calories and exercising. Within hours, Carl is profoundly emaciated, brittle, and turning into a Brundlefly-like horror, because, as Frylock discovers, he's on the South Bronx Parasite Diet, and has been ingesting larva that are now feeding on his flesh. At the end, a giant parasite erupts out of him, splitting his body in two, and weighs what's "left."
- Used in an episode of Freaky Stories. A woman buys a new mysterious diet pill in preparation for a beauty contest, on the condition that she must not drink water for the duration of the diet. The diet pill was actually filled with several tiny sponges, and when she breaks and drinks gallons of water, they cause her to bloat uncontrollably.
- Played for Laughs in the UPA short "The Rise of Duton Lang," where the eponymous portly chemist starts taking a weight-loss additive of his own invention after an embarrassing incident at an awards ceremony. The compound does cause him to lose weight... but not volume. And it works so well that when Lang stops taking the stuff he still loses weight, and eventually becomes lighter-than-air and floats away, never to be heard from again.