Thinner

Thinner is a 1984 novel by Stephen King, published under his Richard Bachman pseudonym.

Obese lawyer Billy Halleck, charged with vehicular manslaughter after killing an old Gypsy woman, is acquitted thanks to his connection with the judge. As he leaves the courthouse, the 106-year-old father of the woman places a curse on him that causes him to rapidly lose weight. After learning that the Gypsy placed a curse on the judge (making him grow hideous scales on his face) and his other friend, a cop that lied on the stand to aid him (leaving his face pockmarked with huge zits), Halleck enlists the help of a former client and mob boss to terrorize the Gypsy to lift his curse.

Made into a movie in 1996 with Robert John Burke as Halleck, Joe Mantegna as the mob boss, and Kari Wurhrer as a Gypsy (the ancient one's great-granddaughter, to be precise).

Thinner contains examples of:

 * Arc Words: After the old gypsy derisively calls Halleck "White Man from Town", he uses the phrase to intimidate them into taking the curse off.
 * As Long As It Sounds Foreign: The passages supposedly in the Romani language are, in fact, in Swedish, and mostly gibberish.
 * Asshole Victim: Halleck, the judge and the cop.
 * Auto Erotica: Halleck hit the old woman because his wife was giving him a handjob while he was driving.
 * The movie changes it to a blowjob.
 * Body Horror: The curses. Given that Halleck is the main character, we get to hear exactly what the Thinner curse entails - a weight loss of two pounds a day. Great if you are a morbidly obese man, as Billy is when the novel begins. Not so much when he starts to lose too much weight. Protruding bones, headaches, brittle hair, jaundice... which all happen to be symptoms of Anorexia Nervosa. Despite not having an appetite at all (it's left up in the air whether or not it's a side effect of the curse, or Halleck's own guilt) he eats like a horse anyway because when he once skipped a meal, instead of losing two pounds, he lost three.
 * Celebrity Paradox: Halleck's doctor tells him at one point that he's "starting to sound a little like a Stephen King novel". (King originally published that book under his Pen Name Richard Bachman, and made this reference to throw people off.)
 * Creator Cameo: Stephen King appears as Dr. Bangor, who owns the pharmacy outside where the accident happened.
 * Cursed With Awesome: Billy Halleck is cursed to rapidly lose weight even if he consumes eight thousand calories in one day, which is awesome at first because he was originally overweight and at high risk of heart problems. However, once it gets to the point where Billy is rapidly approaching the underweight category, and again at high risk of heart problems, the "Awesome" element is dropped entirely.
 * Driven to Suicide: The judge and the cop eventually both kill themselves..
 * Fat Bastard: Deconstructed. Billy Halleck is a seemingly nice guy with a good marriage and is a doting father (his daughter in fact prefers Billy to her mother). However, he is clearly aware of his firm's tie to The Mafia, and is in fact good friends with a man who may be the head of the local mob family. After the accident, he doesn't deliberately use his connections to get him out of trouble, but he does nothing to dissuade them either. There is blame enough to go around, but no one is willing to accept the consequences for their actions.
 * Fat Suit: Burke had to wear one to play the obese lawyer at the beginning.
 * A Friend in Need: When his wife fails to believe he is cursed (and in fact conspires with a local doctor to commit him to a Mental Institution should he return home), Billy turns to Richie Ginelli, a Mafioso who he is acquainted with. Richie sends Billy a doctor, then shows up himself to wreck havoc on the Gypsies until the they agree to lift the curse.
 * Gypsy Curse: Three, to be precise: The titular one, the "lizard" one on the judge, and the mega-acne one on the cop.
 * Hey, It's That Guy!: Who'd have thought that Fat Tony would be willing to help out Robo Cop 3 with his curse problem?
 * He probably should have stuck to helping track down Un-Subs.
 * Hot Gypsy Woman: Gina Lemke is one. Kari Wuhrer plays her in the film.
 * Impaled Palm: Gina shoots Halleck through the hand with a slingshot.
 * Irony: Deliberately invoked by the curses Taduz Lemke inflicts...
 * Lizard - Judge Rossington's curse. Causes him to grow scales all over his body due to his cold-blooded nature.
 * Unknown - Sheriff Hopley's curse. The name of the curse was not given, but it causes horrendous acne to crop up on Hopley's face, neck, and back.
 * Thinner - Billy Halleck's curse. Causes him to drop two pounds a day... until he is erased completely. It's initially a boon due to Halleck's morbid obesity, but he quickly learns that the weight loss will never stop on its own...
 * Additionally, Billy Halleck's doctor was initially advising him to lose weight to prevent his getting a heart attack. Once Halleck loses enough weight, he actually comes closer to dying of a heart attack than he ever did when he was overweight.
 * Karmic Twist Ending:
 * The movie pushes it towards a Cruel Twist Ending with the added subplot of
 * The Mafia: Halleck's friend, Richard Ginelli is an Italian mob boss, who uses his connections to terrorize the Gypsies.
 * My God, What Have I Done?: Halleck says this almost word-for-word in the movie, when he finds out that
 * Never My Fault: Billy Halleck blames everybody but himself for his having run Susanna Lemke over, including Susanna herself.
 * Playing Gertrude: Irma St. Paule, who played the woman Halleck runs over in the film, was one year older than Michael Constantine, the actor who played her father. (Of course, it is hard to find 106-year-old actors, and the guy isn't supposed to look 106.)
 * Redemption Equals Death:
 * Roma
 * Sympathetic Murderer: Taduz Lemke. He inflicts one unique Gypsy Curse each on three people, with the full intention of it killing the victim, in one way or another. And yet he's doing this to avenge his daughter's death at the hands of a white town man when the supposed justice system failed to properly do this.
 * Weirdness Censor: Billy's wife, his physician, and the specialists he goes to see refuse to believe that Billy is cursed, despite finding nothing wrong with him in any of their tests. Averted by Richie Ginelli, who believes Billy upon seeing him and hearing his tale. Richie implies that he can accept a supernatural cause because of stories his grandparents have told him.
 * Villain Protagonist: Billy Halleck, who is dealt a Gypsy Curse and uses desperate means in an attempt to get it off... and yet clearly is enough of an asshole that he deserves it.