Now, it seems, their little sisters are following suit.
"I think we're seeing eating disorders in younger and younger individuals as young as 5 or 6," says Dr. Ira Sacker, director of the eating disorders clinic at Brookdale University Hospital in Brooklyn, N.Y., and co-author of "Dying to Be Thin.""Children are more dissatisfied with their bodies than about getting sick, losing a parent, dying from an atomic bomb," Sacker says, citing results of surveys on the topic. "That's how insane this is."
As many as 10 million adolescent girls and women in the United States have some type of eating disorder, experts say. The most common forms are anorexia nervosa, which involves self-starvation and excessive weight loss, and bulimia nervosa, characterized by binge eating followed by self-induced vomiting, or purging.
But children make up "a good 10 percent" of those millions, Sacker estimates. "And if they don't have full-blown eating disorders, then they have disordered eating behaviors moving in [that direction]."
"It's not about food but about self esteem," he says. "It's about how we feel about ourselves. And our body esteem is terrible."
Sacker recalls treating a 5½-year-old girl who had never been heavy but had been teased by a couple of boys in her class, "so she found a way to decrease her appetite."
The little girl ate paper to fill herself up so she'd have no appetite, he says. And she also "used her room as a race track," he says. "She'd run around her room at night, trying to burn calories."
Apparently she's not alone.
A series of recent studies have shown that 42 percent of first-, second- and third-grade girls want to be thinner, that 40 percent of almost 500 fourth-graders surveyed say they diet "very often" or "sometimes," and that 46 percent of 9-year-olds and 81 percent of 10-year-olds admit to dieting, binge eating or fear of getting fat, according to the Harvard Eating Disorders Clinic in Boston.
Part of the blame for all this, according to Sacker, falls on parents.
"We're seeing second-generation eating disorders now," he says. "We as parents are teachers by example. Kids pick up all the remarks and all the behaviors that we as parents do, and less of what we say."
A child's inclination to imitate mom can spell trouble, experts say, if the mom being mimicked constantly counts calories, exercises fanatically or complains about her stomach not being flat enough or her dress size not being small enough.
Parents obsessed with their own weight or body shape may be sending a dangerous message to their kids, Sacker says. "But we can't project our own issues onto our children," he says. "That's a mistake."
However, parents have plenty of partners to share the blame -- starting with American culture, Sacker says, "where the obsession is that you can't be too thin."
Through music, television, magazines and more, he says, comes the concept that ultra-thin -- meaning someone who wears a size 0 to 2 -- is normal, "rather than recognizing that less than 0.5 percent of individuals even have the ability of being that thin."
"If you don't fit this norm, then that makes you abnormal," he says.
"The media is giving this message, designers are giving the message, families are now preoccupied with their own body image, and, on top of that, we have young people in competition with one another, too," Sacker says. "[Young kids] have major peer pressure now."
Not all eating disorders in children stem from body-image issues, says Maureen Lefton-Greif, a pediatric pulmonologist at Johns Hopkins Children's Center in Baltimore and the liaison with Hopkins' eating disorders program.
"Children have feeding and swallowing problems for many different reasons," she says, ranging from physiological problems that can make it difficult for a child to swallow, to negative experiences associated with eating that have become embedded in their memory, to psychological problems stemming from having witnessed someone choking, for instance.
"So we have to rule out that there's a physiological basis before you can consider whether it's a behavioral or an image problem," Lefton-Greif says.
But she agrees that parents' behavior definitely can affect kids' eating habits.
"I've seen a lot of children [with] feeding problems whose mothers have kept them on skim milk and all those low-fat things because the parent does not want the kid to get too fat," she says. "The body image portrayed by the parent can adversely affect what the kid is given."
What To Do
All parents need to be careful of the messages they may be sending children unknowingly, Sacker says. If you're worried about your weight, for instance, don't talk about it in front of your children because "kids will pick up on it," he says. Parents struggling with their own self-esteem or body-image issues ought to seek help themselves, Sacker says, before they project those problems onto their children.
Also, he says, watch what you say to your kids. "Simply saying, 'You could stand to lose a couple of pounds,' could trigger an eating disorder," Sacker says.
And if your child suspects a friend has an eating disorder, check out KidsHealth.