Jessica Silk, a wavy-haired, freckled grad student in public health, was sitting at the Organic Grille in the East Village on a recent sun-drenched afternoon, picking at a healthful seitan wrap. “Sometimes I think we can smell one another in a crowd, and not because we have snacks,” she said.

Ms. Silk, 27, was talking about former fat kids, of which she is one. Have you ever noticed how New York is simply swimming with these psychologically fragile souls? You can see it in the careful attention to what’s on their plates ... their slavish devotion to daily exercise routines ... and the slightly nervous look that creeps into their eyes now, as bikini season looms.

David Zinczenko, editor of Men’s Health magazine since 2000 and co-author of Eat This, Not That: Thousands of Simple Food Swaps that Can Save You 10, 20, 30 Pounds—or More (Rodale Books, $19.95), is one prominent former fat kid. “The stigma of the overweight child never really leaves,” Mr. Zinczenko, who grew up stocky in Bethehem, Pa., wrote The Observer in an e-mail. “For some of us, the escape from the fat shroud is what defines us.”

And arguably, some never really escape. “I still think of myself as a fat little dorky kid from Orange County desperately wanting to be cool,” No Doubt songstress Gwen Stefani told Grazia magazine in 2007. Ms. Stefani works out a few hours a day to fend off this inner fat kid. “It takes a lot of effort for me to look like this,” she said. “If I slack off, it really shows. That little chubby kid starts coming out and I have to rein her back.”

Think, too, of the prototypical FFK Bill Clinton bonding with FFK Monica Lewinsky, the suggestion of blubber hovering around him even after bypass surgery years later. “I was the fat band boy,” he said to CNN in 2005, upon founding the Alliance for a Healthier Generation with the American Heart Association, which was swiftly joined by another former Arkansas governor, Mike Huckabee (who grew up chubby thanks to Baptist potluck suppers, but lost 105 pounds in one year by jogging).

Current candidate Barack Obama has fared better ... or has he? In his younger days, he was known simply as “Barry,” a roly-poly kid who read comic books and was often challenged to street fights. Now, he looks like he could use a good helping of grandma’s meatloaf. Surely Mr. Obama’s lean figure is correlated, in part, with charges that he is “elitist.” Middle America likes their politicians to look like them—with a nice spare tire around the waist—or so the theory goes.

Trembling at the Times Cafeteria

But back in New York, of course, it’s socially impermissible to be anything but thin.

This is the metropolis where the leggy-legged and skinny-armed women and flat-abbed men come from all over the world to model. Instead of brain drain, in which smart people leave their countries to make it big in other ones, we have fat drain, where thin people infiltrate Manhattan and create a kind of alternate universe where hip bones are as sharp as knives and biceps are bulging.

“Does this city make my ass look fat?” Stephanie Vann, 42, recently screeched in a Manhattan Starbucks. Ms. Vann, a FFK who grew up on Park Avenue as Stephanie Winston, the great niece of jeweler and “king of diamonds” Harry Winston, was on the phone from her current home in Ithaca, N.Y.

“All of a sudden, you go to a Starbucks in the city and everyone looks like they’re between an Equinox and a callback for The Nanny Diaries or something,” she said. “Nobody looks real in any sense of the word.”

Young Stephanie was ridiculed by classmates at her private school, Birch-Wathen. She was “10 or 15 pounds overweight,” she said. “But growing up in Manhattan, on Park Avenue, even five pounds overweight was just too much.”

She spent the better part of a decade in and out of fat camps. Diagnosed with breast cancer in 2005, she went from her regular weight of about 130 pounds to 96 pounds. “I’d go clothes shopping. … I was so happy that I needed to ask for a zero,” she said. “People thought I was either anorexic or had a coke addiction. But I felt so good being so skinny for the first time in my life.”

Ms. Vann fled the city in the ’90s for college, then a boyfriend. But many FFKs seem to congregate in New York, where they can make a brand new start of it and escape their plumper pasts. It’s conveniently a walking city. (Burns lots of calories!) There’s the farmers’ market, raw-food-only restaurants and a gym on every corner.

Of course, there are also pizza joints ... noodles shops ... Beard Papa.

“I feel like I’m one Hostess cupcake away from losing control,” said Abby Ellin, a freelance writer for The New York Times and women’s magazines and author of Teenage Waistland: A Former Fat Kid Weighs In on Living Large, Losing Weight and How Parents Can (and Can’t) Help (PublicAffairs, $12.95).

Ms. Ellin, 40, keeps a toned, slim figure now. But she was a husky gymnast in her teens, eating Duncan Hines chocolate frosting straight from the container and occasionally devouring a box of Ring Dings in an hour. “I like to call myself a failed bulimic,” she said. “I had mastered the binge but never perfected the purge. People in high school tell me, ‘But you weren’t fat,’ and I get really angry, because that’s the way I was made to feel in my family, and my identity at the time was wrapped up in being a fat kid.” And she still feels like the fat girl, the outsider. When she goes to the Times cafeteria, she’ll find herself looking around the room at the cliques of writers or editors chomping on salads and sandwiches. And she’ll wonder why it suddenly seems like she’s stuck in a John Hughes movie. (Is there a relationship, one wonders,between being a FFK and being a freelancer?)

“Being a fat kid shapes your identity,” Ms. Ellin said, “because the world is one big high school.”

Diabolical Diet Docs

Blogger Stephanie Klein, a Long Island native, has also written about being a FFK; her book Moose: A Memoir of Fat Camp, will be released at the end of May by publisher William Morrow.

“A lot of overweight kids, and adults, have what I call the someday syndrome,” Ms. Klein said. “They think someday in the future everything will be fixed and brighter because you’re thin. It never works that way.”

Ms. Klein, who now lives in Austin, Texas, remembered being treated by a diet doctor in Manhattan “who would stab your arm with a B vitamin” and “yell at you if you gained weight.”

“Before I’d go there, I would practically starve myself to make up for the times I was bad,” she said poignantly. “I would take these water tablets, they’re like $100 for a bottle, and I would take them to get rid of the water weight so he wouldn’t yell at me.”

Ms. Klein lost about 20 pounds with the doctor, but realized that her husband was cheating on her with women all over the city. Later, she gained the weight back.

“I still will always think of myself as the fat girl,” she said. “I think there’s a real sensitivity that’s kind of tattooed on you when you’ve grown up as the fat kid. If I ever hear anyone say someone is fat, I jump on the chance to correct them, not to make them feel bad, but to dismantle a lot of things people think and say.”

Perhaps fat kids are so ridiculed and chastised because some unfairly see them as a physical manifestation of weakness. Many people can hide their vices and addictions (whether it’s sex, like the promiscuous Spitzers of the world, or gambling, drugs, pornography, shopping). But the fat kid’s tragedy is made flesh, hanging over too-tight jeans and spilling from ill-fitting tops.

Maybe it’s this very public humiliation that makes FFKs more ambitious than average, eager to quiet the taunts that still ring in their heads—yet also, somehow, more compassionate.

“There’s a reason I’m not the editor of Esquire or Guns and Gardens,” Mr. Zinczenko told The Observer. “I choose to work for a magazine that can help people.”

“There’s always that part of me that needs to ‘prove’ that all those jerky kids were wrong,” Ms. Silk said. “I learned to be funny and artistic because I needed to attract people in a way that ‘made up’ for the fact that my looks weren’t my prized possessions. In that regard, the symptoms of being the ‘fat kid’ will always be part of who I am.”