This finding is so disturbing to me, Dr. Julie C. Lumeng from University of Michigan, Ann Arbor, who led the study, told Reuters Health.

She also admitted being a bit surprised. Unlike in the 1980s, she explained, so many kids are obese now. In some schools, half the class may be overweight...so I really thought that maybe being obese really doesn't result in being bullied as much anymore. I was wrong.

The study involved 821 US boys and girls 8 to 11 years old. In third grade, 17 percent of the children were obese and 15 percent were overweight.

A quarter of the children reported being bullied, although their mothers said about 45 percent of them were bullied.

According to the investigators, the odds of being bullied were 63 percent higher for an obese child, compared to a healthy-weight peer.

The higher odds of being bullied among obese children were equally strong for boys and girls, white and nonwhite children, children from poor and more well-to-do families and across all types of schools in all 10 study cities, the investigators note.

Lumeng also thought she'd find protective factors -- like having good social skills and doing well in school. I thought maybe this would protect obese kids from being bullied. But no matter how we ran and re-ran the analysis, the link between being obese and being bullied remained, Lumeng said.

Parents of obese children rate bullying as their top health concern, Lumeng and her colleagues note in their report, and obese children who are bullied suffer more depression, anxiety and loneliness.

The issue has received more attention since the suicide of 15-year-old Phoebe Prince in January. Prince was reportedly bullied for months by students at her high school in South Hadley, Mass.

There is no simple solution to the problem, Lumeng told Reuters Health. I think it reflects the general prejudice against obese people, and children, even at a very young age, pick up on this.

On a societal level, it is important to fashion messages aimed at reducing the premium placed on thinness and the negative stereotypes that are associated with being obese or overweight, the investigators write in Pediatrics.

Lumeng is also concerned about the pervasive view that obesity is all about a lack of self-control with food and not getting enough exercise. And while overeating and lack of exercise are part of it, it's so much more complex than that, Lumeng said, and we really need to work on changing this view of what causes obesity.

Dr. Matthew Davis, who was not involved in the study, agrees. In an email to Reuters Health, he said he would encourage adults to model good behavior for children, by not making negative comments about other people's weight.

Schools are increasingly addressing the problem of bullying, but programs don't always -- or even frequently -- include kids' weight as a focus for bullying prevention, noted Davis, who directs the CS Mott Children's Hospital National Poll on Children's Health at the University of Michigan, Ann Arbor. With obesity affecting 1 in 5 to 1 in 6 kids in the US, parents can encourage schools to make sure that bullying related to obesity is targeted in intervention programs, he added.