A friend’s 8-year-old daughter packs her own lunch for school. One day, her dad noticed that lunch consisted of a single cherry tomato, one slice of apple and one spoonful of yogurt. When asked, the child replied that she didn’t think she’d be hungry at school.

My friend wanted to know: Was this the beginning of problem eating?

Eating disorders such as anorexia, bulimia and binge eating most commonly emerge during the adolescent years, says Claire Mysko, the chief executive of the National Eating Disorders Association. “But we’re hearing about younger and younger cases,” she says.

How young? As young as 5 years old, according to the American Academy of Pediatrics, which updated its guidelines on preventing eating disorders and obesity in teenagers last year. Approximately half of teenage girls and a quarter of teenage boys are dissatisfied with their bodies, according to the AAP.

“The stereotype is of a young white thin girl. It’s a common misperception,” Mysko says. “These illnesses occur in all sizes, all races, all genders, all ages.”

If you see signs that concern you, don’t dismiss them, Mysko says. Such signs might include a child who cuts out an entire food group or one who seems anxious at mealtime. Talk to your pediatrician about your concerns.

Pediatricians will look at kids’ growth curves, measuring height and weight at well-child visits to ascertain that growth is on track. They’ll also ask kids whether they eat fruit and vegetables, whether they eat a variety of colors and whether they try new things. By doing so, they’re checking for potential problems and promoting good eating habits.

“It’s normal to expect picky-eating episodes,” says Lynne Lillie, a family physician in Rochester, Minn. “Kids can seem hungry one day but not at all the next.”

My friend did not dismiss the signs. She talked to a friend with some expertise, she watched her child eat at home, and she kept an eye on lunch content. An already scheduled well-child visit was coming up soon.

My friend said she felt that she and her husband were doing many things right. They offer a variety of fresh foods and let their kids decide how much to eat. They don’t promote a particular body size or talk about dieting.

This aligns with current advice. Through their actions, parents should be modeling messages of healthy eating and positive body image, Lillie says.

What else can families do to encourage healthy eating?

Avoid putting emphasis on weight. This is a key recommendation of the AAP guidelines.

Losing weight should not be a goal. Nor should “losing a few pounds” or “getting thinner” be associated with hopes for greater happiness or popularity. A parent who talks about weight — their own or their child’s — is a risk factor for eating disorders.

Teasing a child about his or her weight is not good. This may seem obvious, but remember that such teasing might come from any source — parents, siblings or schoolmates. Statistics reported in the AAP document indicate that 40 percent of 13-year-old girls have experienced this. Such teasing puts boys and girls at risk for becoming overweight, and it increases a girl’s chances of such disorders as binge eating and extreme weight-control behaviors.

“The focus on weight,” Mysko says, even when it is well intentioned, “can backfire.” Indeed, she says that dieting is a major risk factor for developing an eating disorder. “Not everyone who goes on a diet will get an eating disorder, but the restrictive mind-set is very much linked to eating disorders.”

“Move away from the idea that there are good foods and bad foods,” Mysko says. “This leads to a feeling of indulging — of saying, ‘I’m bad,’ or ‘I’m giving up.’ ”

Instead, Mysko advises having conversations with your kids about food, exercise and overall health. “Shift attention away from the numbers. Emphasize that good food makes your body feel good. Exercise makes your body strong.”

Talk to your kids about media messages relating to self-esteem and body image. Ask them what they notice about TV commercials and celebrity pages in magazines, including images altered by airbrushing and digital photo editing. Talking about these things can help kids become critical viewers rather than allow them to internalize faulty messages about body image.

One of the most important things parents can do is eat with their kids. A 2007 study of 1,710 high school students found that those who ate most often with their families consumed more fruit and vegetables and fewer soft drinks than other students. Further, these healthy eating trends were maintained into young adulthood.

A 2010 study of 13,000 kids ages 9 to 14 found that regular family dinners were protective against disorders including purging, binge eating and frequent dieting.

If you have a concern about a possible eating disorder, start with a visit to your pediatrician, who may recommend a therapist specializing in eating disorders. Educate yourself; the National Eating Disorders Association website has lots of information, including a tool kit for parents.

But do something. “Early intervention makes a huge difference,” Mysko says. “The sooner you can address the behavior, the more effective treatment will be.”