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. Maybe he meets an unusual stranger on the street with slimming abilities. The point is, he loses weight (or at least takes steps to do so).
And 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. 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:
- In X-Men, whoever is chosen as Famine in Apocalypse's Horsemen can cause people to become emaciated by touching them.
- 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.
- 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.
- An old Marvel comic 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 Vault of Horror story Dying to Lose Weight!, a traveling doctor offers to help a towns 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.
- In the French comic Melusine, the titular 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.
- 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.
- In My Best Friends Exorcism, Big Beautiful Woman Margaret is obsessed with losing weight and constantly goes through fad diets. Gretchen - who is possessed by a demon - convinces here 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.
- "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.
- 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 works great. But then he realizes that for every pound he loses, the monkey gains one, and as it grows bigger its power and malevolence increase as well.
- 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.
- Thinner, by Stephen King: A fat lawyer is cursed by a gypsy to lose weight. As in, all of it.
- 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.
- The Goosebumps book "Say Cheese and Die Again!" has this trope both Played Straight and Inverted. 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.
- 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.
- 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 Kazar 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.
- 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.
- In the Smallville episode "Craving", bullied, overweight teen Jodi takes Kryptonite 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. She eats everything in sight trying to keep weight on. 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. Unfortunately, it also kills them.
- 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 psychic duel ("SCAN ME!"), which ends in the man bleeding from the forehead and passing out.
- A Played for Laughs example is Bob from Tekken series, an acrofatic character that likes his overweight status. However, in his Tekken 6 ending, after all the effort to win the King of Iron Fist Tournament, he suddenly lost 150 pounds, becoming slim, which was a shock for him. Bob thinks his weight loss was a curse to him, losing also his strength and speed gained with the training that made him fat. First being a cameo, later this becomes a separate character in Tag Tournament 2 as "Slim Bob".
- NOT played for laughs in Red Dead Redemption 2. The player is treated to gradually watching the tall, broad-shouldered and tough-as-nails cowboy Arthur Morgan gradually waste away to nothing from tuberculosis, a bacterial infection that was a death sentence for anyone who contracted it in 1899. It's actually possible for him to become more underweight than the game normally allows.
- 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.
- 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.