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Study: Poor exercise habits don't explain failing obesity tests

Category: General Health

Though scientists estimate that nearly one third of children and teens in the U.S. are overweight or obese, a lack of exercise does not explain the rising rates, a new study suggests.

An examination of government survey data by researchers at Johns Hopkins University in Baltimore determined that between 1991 and 2007, U.S. teens have averaged more time in gym classes and less time watching television than in earlier periods, Reuters Health reports.

According to the investigators' report, published in the journal Obesity Reviews, exercise levels are "not likely the major explanation of the recent increase in obesity among U.S. adolescents."

Overall, Dr Youfa Wang and colleagues found that 35 percent of teenagers surveyed in 2007 met current recommendations for physical activity, defined as any activity that raises the heart rate for at least one hour each day, five or more days a week.

Additionally, a total of 30 percent of high school students took daily physical education classes in 2007, up from 25 percent in 1995, and 35 percent watched three or more hours of TV in 2007, down from 43 percent in 1999.

"Although only one third of U.S. adolescents met the recommended levels of physical activity," Wang told the news source, "there is no clear evidence they had become less active over the past decade while the prevalence of obesity continued to rise."

Rather, the researchers hypothesize that unhealthy diets may be the operative force behind climbing obesity rates among teens.

Diet, exercise…anxiety?

Though poor diet and lack of exercise are two well-know factors which may contribute to obesity, scientists have found that less perceptible sources may play a role as well. Researchers from the MRC Social, Genetic and Development Psychiatry Center at King's College in London found that children who experience emotional distress are more likely to become obese in adulthood.

According to the study, ten-year-olds who expressed low self-esteem and high anxiety were more likely to gain significant weight over the next 20 years than their less anxious counterparts.

The study's lead researcher David Collier told BBCNews, "What's novel about this study is that obesity has been regarded as a medical metabolic disorder - what we've found is that emotional problems are risk factors for obesity" as well.

According to The Centers for Disease Control and Prevention (CDC), the prevalence of the condition in 12-year-olds to 19-year-olds increased from 5 percent to 17.6 percent between 1976 and 2006.

Beyond baby fat

While obesity is commonly linked with poor heart health, a growing body of research suggests that the condition may contribute in the increased occurrence of strokes, multiple sclerosis and cancer.

Recent testing performed by the American Institute for Cancer Research determined that more than 100,000 cases of cancer each year are caused in part by excess body fat, according to CNN. Specifically, the study found that about half of endometrial cancers and 35 percent of esophageal cancers are caused by obesity.

In teenage girls, clinical obesity more than doubles the risk of developing multiple sclerosis, compared to slimmer teens, HealthDay News reports.

"Up until recently, we've looked at MS as a disease for which the onset can't be controlled," researcher Dr John Richert told the news source. "If all the incoming data from this study is correct, not smoking and maintaining an ideal weight might lower the risk of MS."

WebMD reports that blood tests for high cholesterol or triglyceride levels and additional testing for body mass index may help doctors diagnose obesity, diabetes and the complications which accompany the conditions.

According to the CDC a body mass index of 18.5 to 24.9 is considered normal, while any measurement above 30 constitutes obesity.