Formerly Fat

A character that used to be fat, but now isn't.

Sometimes, part of a character's personality is driven by the fact that they were once overweight. Having a thin character revealed to have once been fat can tell you plenty about them; it can tell you that they had a past they aren't proud of and cares enough about their health and appearance to do something about it. It also shows that the character has the strength and will power to take control of their life and get what they want, that they have the ability to self-discipline and self-motivate.

Be that as it may, a formerly fat background is not always all sunshine and rainbows. It can also imply a lot of self loathing and damaged self esteem, too. Many times, their slim down can be a symptom of a desperate need to be accepted by society and an unhealthy dependence on what others think of them. The two attitudes are not mutually exclusive either, leading to many Formerly Fat individuals to have complicated self-images.

Anime & Manga

 * Fatman's teenaged little sister in the Ratman manga is conventionally slender now, thanks to years of dieting. She does not like it when her big brother shows people pictures of her as a chubby child. (Fatman is the "jolly" type who doesn't understand why she's so ashamed of her past.)
 * Overweight Reika from Ginga E Kickoff is accepted in a soccer team mainly because they need one more player to be legal for an upcoming tournament. She eventually becomes more fit.

Film

 * In Get Smart, Maxwell proudly shows an old picture of himself to Agent 99, wherein he weighs much, much more than he does at the time. We see a short flashback wherein he exercises rigorously so he can have the proper shape to be an agent of CONTROL.
 * In Drag Me to Hell, we learn that Christine was crowned "Pork Queen" at a county fair as a child. This ties into the film's anorexia subtext.
 * Matilda from Zoolander.
 * The Eddie Murphy version of The Nutty Professor turns into a thin Buddy Love.
 * At the end of Austin Powers in: "Goldmember", Fat Bastard isn't fat anymore, because he went on the Subway diet. However he doesn't look that much better since he now has a lot of loose hanging skin.
 * Ryan Reynolds' character in the film Just Friends was really obese in high school.
 * Debbie Salt in Scream 2 used to weigh 60 more pounds.
 * Joan Cusack's character in In and Out is stated to have lost a ton of weight before the movie started.
 * Alyson Hannigan in Date Movie.

Literature

 * Anita from Anita Blake Vampire Hunter mentions having been fat in middle school.
 * Ben Hanscom of Stephen King's IT was fat as a kid, but ended up slimming down as an adult by the time that he and the Loser's Club meet up again to battle It.
 * Robin Wilson of Sweet Valley High, always referred to as "formerly fat Robin" in the livejournal snark community 1bruce1.
 * Fat Charlie Nancy of Anansi Boys, who was fat for just long enough to acquire the nickname. It stuck.

Live Action TV

 * The reality series The Biggest Loser attempts to invoke this trope in their competitors.
 * Monica from Friends was definitely this.
 * In "The One with the Rumor", she invites her old high-school friend, Will for Thanksgiving, who used to be so fat that Monica was his "thin friend". In present day, he's played by Brad Pitt.
 * An episode of Law and Order SVU dealt with a girl who was sodomized and beaten. When they found the motive behind the attack, it turned out she herself had attacked and beaten an obese man (her own attackers being relatives of his taking revenge). She took part in victimizing the man because of her own self loathing and anger at herself for having once been like him.
 * I think Maya on Just Shoot Me was fat as a youngster but I'm not sure about that.
 * On Maury one of the frequent themes is "I used to be [fat / a geek / etc.] but look at me now!" where they bring in people who used to tease the person in grade school, to show off to them.
 * On Heroes, the real body of Shape Shifter Candice is a lumpy mess named Betty.
 * A patient on House, who was formerly morbidly obese and had become a highly successful personal trainer.
 * Surprisingly,  from Glee. It's part of the reason she's so obsessed with "perfection" - once she entered high school, she changed nearly everything about her appearance and strived to keep it that way.
 * On Boy Meets World, Jack Hunter is revealed to have been fat in high school, to the point that people called him "Jumbo Jack". He explains that this is why he goes to the gym so much and is obsessed with his looks.
 * The main antagonist from the 5th season of Dexter was overweight as a child.
 * The Palace had the attractive and thin Alice Templeton, better known to her childhood friends as "Fatty".
 * J Pod had Kaitlin Joyce: she even starred in a TV commercial promoting the "miracle diet" that helped her out. It shated more than a few traits with the Subway ads.
 * Mary from 3rd Rock From the Sun was fat as a kid, and has a lot of issues with her parents about it to boot.

Video Games

 * In Persona 4, Ai Ebihara, the Moon Social Link.

Web Comics

 * Hanae of Red String started with a formerly fat background. As the story has progressed, she's put a lot of the weight back on. She puts a lot of her self worth on being pretty in other people's opinions. Her mother's vision of her as a girlie princess takes a huge toll on her.
 * Raven of Questionable Content was mentioned to have been a bit on the heavy side before the comic started. She's a bit sensitive about it, so no one brings it up.
 * Sharon of General Protection Fault used to be much heavier than she is. Some harsh comments made to the obese Dexter regarding his weight cause him to nearly turn down a full-time position at GPF, but Sharon was motivated by concern for him and apologizes.

Web Original

 * The Nostalgia Chick was once a fat, wangsty Emo Teen who listened to Phantom of the Opera because he knew her pain.
 * Now Lean and Mean, Ask That Guy With the Glasses used to be the size of a bulldozer and felt dead inside.

Western Animation

 * Amy Wong from Futurama was very fat as a child; even her parents tease her mercilessly about it. In one episode, the main characters all revert to their childhood forms, and Amy, again overweight, becomes the butt of all her parents' childish jokes.
 * Heather from Total Drama Island has been stated to have been a fat, unpopular, brace-faced dork in middle school. It's possible that her experiences with bullying contributed to her cutthroat personality.
 * Connie Benge on Doug used to be chubby, but in later seasons it's revealed she lost a lot of weight at summer camp.
 * Nazz from Ed, Edd n Eddy, who's the resident hottie, was revealed to be quite heavy when she was younger.
 * In Producing Parker, various Flashbacks and Embarrassing Old Photos show Parker as fat from infancy to her teens.

Real Life

 * Jared, the Subway diet spokesman, pictured above.
 * Raven Symone
 * Inverted.
 * Richard Simmons (or so he claims).
 * Star Jones, a recent and rather dramatic example.
 * Stuart Pankin.
 * Peter Jackson.
 * Jerry O'Connell. Hard to believe he started out as the fat kid on Stand By Me.
 * The MTV reality show I Used to Fat is based off this trope - overweight high school seniors are given trainers to make them skinnier before going to college.
 * Drew Carey.
 * 1998-2006 Saturday Night Live cast member Horatio Sanz. A quick Google Image search should give you an idea.
 * Sara Rue
 * Al Roker from Today on NBC.