Parents of overweight teens and their doctors should not focus on the number on the scale because negative talk about weight can be harmful, a U.S. pediatric group says.

The American Academy of Pediatrics advised its members and parents to focus on encouraging healthy behaviours to help teens avoid obesity and eating disorders.

The academy developed the guidelines in response to growing concern about teenagers' use of unhealthy methods to lose weight.

The new recommendations include strategies adults can use to help teenagers avoid both obesity and eating disorders. They apply to all teens, not just those with weight problems.

Three recommendations focus on behaviours to avoid:

Parents and doctors should not encourage dieting.

Avoid "weight talk," such commenting on their own weight or their child's weight.

Never tease teens about their weight.

"If the kid sees a lot of dieting behaviours around their parents, it can unfortunately lead to [thinking] this is sort of the norm and that we put a lot of value on body image," said Dr. Christine Wood, a pediatrician in San Diego, Calif., who helped develop the recommendations. "For young teens this can become an issue, and many of the kids that we see with eating disorders, it starts with sort of a body image issue."

Brenndon Goodman of Toronto said constant talk about his weight strained relations with his parents. He weighed more than 300 pounds by his mid-teens.

The university student recalls going to his doctor and being told to lose weight. Goodman would then go on a diet that would last about a week.

Pushing an agenda on a teen about food and how much weight they should lose can spiral into the wrong behaviours from the child, Wood said.

Unhealthy lifestyle the problem, not weight

Goodman commends the academy's recommendations. "It's not about the weight. It's not about the numbers."

Fundamentally, pediatricians say, the problem is thinking of weight as the problem when unhealthy lifestyle is the true problem.

Two of the group's recommendations focus on behaviours to promote:

Families should eat regular meals together.

Parents should help their children develop a healthy body image by encouraging them to eat a balanced diet and exercise for fitness rather than weight loss.

In Goodman's case, in 2012 he underwent bariatric surgery and lost a third of his weight. He admits he has more work to do.

The recommendations were published in this week's issue of the journal Pediatrics.