WEDNESDAY, July 28 (HealthDay News) -- Obesity is associated with early puberty in young girls, according to a researcher who analyzed more than 100 reports on the issue.

Some experts have concluded that early puberty increases the risk for metabolic syndrome and diabetes, but these diseases are linked to obesity, not early puberty, according to review author and pediatric endocrinologist Dr. Emily Walvoord, of the Indiana University School of Medicine.

"Early puberty is one of the many outcomes of obesity. There are clearly other factors we don't understand that have affected the timing," she said in a news release from the Center for the Advancement of Health.

These other factors may include an increase in hormone-disrupting chemicals in the environment and more chronic stress in children's homes, she noted.

Early onset of puberty puts girls at increased risk for negative body image, depression and other mental health issues. But these problems are also closely linked with obesity, so it's difficult to untangle cause and effect, Walvoord said.

The review appears online in the Journal of Adolescent Health.

Girls who reach puberty early can also end up in social situations they aren't psychologically prepared to handle, which may lead to mental health problems, said Jane Mandle, a psychology professor at the University of Oregon.

More information

The Nemours Foundation has more about early puberty.