A new study has found that obese children, especially girls, show signs of the negative consequences of being overweight as early as kindergarten.

"We found that both boys and girls who were overweight from kindergarten through third grade displayed more anxiety, depression and loneliness than kids who were never overweight, and those negative feelings worsened over time.

"Overweight is widely considered a stigmatizing condition and overweight individuals are typically blamed for their situation. The experience of being stigmatised often leads to negative feelings, even in children," Sara Gable, who led a research team at University of Missouri, said.

For the study, the researchers analysed the Early Childhood Longitudinal Study in the US to examine the social and behavioral development of 8,000 school-age children from kindergarten entry through third grade.

The researchers evaluated factors that have not been studied previously -- age at becoming overweight and length of time being overweight. "Girls who were consistently overweight, from kindergarten through third grade, and girls who were approaching being overweight were viewed less favourably than girls who were never overweight.

"Teachers reported that these girls had less positive social relations and displayed less self-control and more acting out than never-overweight girls," said Gable.

The results indicate that larger than average children, especially girls, experience social and behavioral challenges before they reach the 95th percentile of the Body Mass Index and are classified as being overweight.