The epidemic of excess weight gain and obesity among young Americans began about 15 years ago, a new study finds.

"Our research documents the emergence of the obesity epidemic among adolescents in the later half of the 1990s, and among young adults in 2000," said Hedwig Lee, who led the study while at the University of North Carolina at Chapel Hill. She is now an assistant professor of sociology at the University of Washington in Seattle.

"The jury is still out about all the possible causes for the increasing weight gain among adolescents . . . as well as for the entire population," said Lee.

However, she cited a number of possible factors, including a rise in time spent in front of computer or TV screens and longer time spent in post-secondary education, "transitioning" to adulthood. According to Lee, poor diet and couch-potato lifestyles rise when young people leave the parental home and go out on their own, before starting their own families.

According to the study, the BMI of the average 18-year-old from 1959 to 1980 stayed relatively stable at 22. However, it had risen to 23 by 1990, and to about 25 by 2000, the researchers found. That would translate into a weight gain from an average of 149 pounds to an average of 166 pounds for a 5-foot 9-inch, 18-year-old male. An average 5-foot 5-inch female's weight increased from 132 to 147 pounds.

Source: U.S. News & World Report
http://health.usnews.com/health-news/family-health/brain-and-behavior/articles/2011/07/21/epidemic-of-obesity-in-us-kids-began-in-late-90s