CHICAGO – Having fast food restaurants in children’s hospitals influences patients’ families to eat fast food and to think that it’s relatively healthy, new research suggests.

At least 59 of the nation’s 250 children’s hospitals have fast-food restaurants, the study found. That is a troubling phenomenon, particularly given rising obesity rates, said the study’s lead author, Dr. Hannah Sahud, a pediatrician at Allegheny General Hospital in Pittsburgh.

“We’re giving two different messages by being in the health care profession and promoting health and saying obesity is a huge medical problem … and then implicitly encouraging it,” she said.

About 17 percent of U.S. children are considered obese and many doctors think heavy consumption of calorie-laden fatty fast food is partly to blame.

Sahud conducted the research while at Chicago’s Children’s Memorial Hospital, which has one McDonald’s inside and another across the street.

Parents of children who got outpatient treatment at Children’s Memorial were much more likely to buy McDonald’s food on the day their youngsters were treated than parents of kids treated at Chicago-area hospitals without McDonald’s.

Parents of kids treated at Children’s also were twice as likely to rate McDonald’s food as relatively healthy than those whose kids were treated elsewhere.

“I was shocked … that they actually perceive it to be healthier,” Sahud said.

Her study appears in December’s Pediatrics, scheduled for release Monday.

“Hospitals should be walking the walk, not just talking the talk,” said Dr. Sarah Barlow, an obesity specialist at Saint Louis University and Cardinal Glennon Children’s Medical Center. She was not involved in the research.

Children’s Memorial spokeswoman Julie Pesch said the hospital chose McDonald’s many years ago as a special treat for sick kids going through difficult treatment.

Pesch said balanced diets can include an occasional fast-food meal, but acknowledged the study shows “doctors and families that we must continue to talk about what constitutes a healthy diet for kids.”

The researchers queried 200 pediatric residency programs in 2002-03. About 30 percent, or 59, had fast-food restaurants in their hospitals. McDonald’s alone or in combination with other fast-food restaurants were located in 22.

The researchers also surveyed 386 parents and other adults leaving three Chicago-area hospitals after their children had outpatient visits.

They were Children’s Memorial; Ronald McDonald Children’s Hospital in Maywood, which uses McDonald’s branding but has no McDonald’s restaurant; and the University of Chicago’s children’s hospital, which has no McDonald’s restaurant or branding on site.

The study found that 56 percent of participants at Children’s Memorial had fast food on the survey day, compared with 29 percent at Ronald McDonald and 33 percent at the University of Chicago. Most at all three hospitals who had fast food that day chose McDonald’s.

McDonald’s has restaurants in more than 30 U.S. hospitals, said spokesman Bill Whitman.