It's a fad that's all the rage among celebrities: losing lots of weight, seemingly overnight.
Valerie Bertinelli and Kirstie Alley each endorsed weight-loss plans and famously flaunted their bikini-ready bodies, though Alley is again battling weight issues. And celebrity magazines have ruthlessly chronicled the ups and downs of stars such as Jessica Simpson and Jennifer Love Hewitt.
But while yo-yo dieting is appealing to many, it's being sworn off by some Americans like Marianne Kirby. She may tip the scales at 319 pounds, but when she looks in the mirror she loves what she sees.
"When I look at myself in the mirror, I see pure awesome," said Kirby, who lives in Orlando, Fla., and is the founder of the Web site TheRotund.com. "Fat is beautiful!"
Though the 31-year-old now weighs 100 pounds more than she weighed 10 years ago when she was aggressively dieting, the newlywed and new author of a book called "Lessons From the Fatosphere" says she's the happiest she's ever been.
"My life is so much better since I stopped dieting," Kirby said. "I'm 100 pounds heavier, but 100,000 times happier!"
Since stopping dieting, she says, she's gained confidence, a new husband, and a book deal.
Gabrielle Gregg, 22, can relate to Kirby's anti-diet mentality.
Her blog, "Young, Fat and Fabulous," is dedicated to weighty women in pursuit of fashion. After trying dozens of diets, from Atkins to the grapefruit diet to Weight Watchers, she now believes there's nothing wrong -- and actually, a whole lot right -- with being overweight.
"I think healthy is not just about your body," Gregg said. "It's about your mental and spiritual well-being. At my lowest weight, I was the most sick I've been mentally and physically in my life. I lost hair, I was having night sweats."
She wrote on her blog, "I'm just trying to change the world one fat girl at at time."
Kirby and Gregg are part of a small but growing movement called "fat acceptance," which embraces the idea that a person's size does not exclusively determine his or her health or self-worth, and that it's OK to be fat.
Gregg, a Detroit native who recently relocated to New York to pursue her dream of working in the fashion industry, says she uses "the F word" -- fat! -- even though it can be a taboo.
"I think that's part of what I wanted to show people -- that I am fat," she said. "I'm not necessarily curvy and not chubby. I'm fat. I'm 220 pounds."
Kirby agrees. "We're fat. And there's nothing wrong with that word. Being fat doesn't mean we're lazy or smelly. We're fat."
But while Gregg and Kirby say they feel healthier than ever now that they've quit dieting, critics -- including the National Action Against Obesity -- say the fat acceptance movement is "reckless," promoting a lifestyle that can have dire health consequences.
Rebecca Puhl, a weight expert at the Rudd Center for Food Policy and Obesity at Yale University, acknowledges being overweight can prove harmful.
"There are a number of common health concerns associated with obesity, including high blood pressure, heart problems, diabetes and some cancers," she said.
But, Pulhl is quick to point out, yo-yo dieting can also be dangerous, resulting in high blood pressure, gall bladder complications and a myriad of psychological problems.