Sept. 8, 2003 -- It's no surprise that kids who drink large quantities of soda or spend too much time in front of the television are more likely to be obese than other kids. But a new study suggests that it's not just the lack of physical activity or sugar in the soda that's to blame.
Researchers found that school children that drink large quantities of diet soft drinks were just as likely as those who gulped sugary ones to suffer from childhood obesity, and watching TV was much worse for their waistlines than playing video games or surfing the Internet.
The study shows that sixth- and seventh-grade students who watched more than two hours of TV a night or drank more than three soft drinks per day were more likely to have a higher BMI (body mass index, a measure of weight in relation to height used to indicate childhood obesity) than others.
The results appear in the September issue of the Archives of Pediatrics & Adolescent Medicine.
Study Sheds New Light on Childhood Obesity
Researchers say the findings suggest that experts still have a lot to learn about the current epidemic of childhood obesity.
The prevalence of childhood obesity has doubled since the 1970s, and obesity is a known risk factor for a number of health problems, including high blood pressure and diabetes.
Although watching television and soft drink consumption have been linked to childhood obesity in the past, the study shows the link runs deeper than previously thought.
"The findings that overweight and obesity were not associated with computer use and that they were associated with diet soft drink consumption indicate that it is neither the sedentary activity alone nor the calories in the soft drinks alone that can be implicated as a cause of obesity," write researcher Joyce Giammattei, DrPH, and colleagues of Loma Linda University.
Instead, researchers say that TV viewing and soft drink consumption may both be indicators of increased calorie intake because of other factors.
For example, television viewing is easily accompanied by eating and also includes frequent food-related advertisements that may induce more eating. In contrast, computer use is less conducive to eating because it keeps both hands busy and there is less exposure to food ads.
In addition, researchers write soft drinks -- diet and regular -- are routinely served with calorie-rich foods, such as high-fat, fast food burgers and fries.
Lifestyle Affects Childhood Obesity Risk
During the study, researchers surveyed 319 sixth- and seventh-grade students in California and collected information on their height, weight, and lifestyle habits.
They found that 35% of the students had a BMI at or above the 85th percentile (indicating being overweight) and half of these students had a BMI at or above the 95th percentile (indicating obesity). BMIs also tended to be higher among Latino students and lower among Asian students compared with non-Hispanic, white children.
The study showed that there was a significant relationship between BMI and both the hours of TV the children watched and the quantity of soft drinks they drank per day. For example:
- Nearly half (47%) of children who watched three or more hours of TV a night had BMIs at or above the 85th percentile.
- Only 26% of students who watched less than two hour of TV per night had BMIs at or above the 85th percentile.
- 58% of students who drank three or more soft drinks (diet or regular) per day had BMIs at or above the 85th percentile.
- 33% of students who drank less than three soft drinks per day had BMIs at or above the 85th percentile.
Researchers also found that Latino children watched more TV per night (an average of 2.4 hours per night) compared with others and drank more soft drinks (an average of 1.6 per day) than other kids.