Most everyone knows by now that drinking a lot of soda is unhealthy. But a study of Texas middle and high school students suggests that many people see drinking other sweet drinks as part of a healthy lifestyle.

Most popular sports drinks contain between half and two-thirds the amount of sugar found in soda, although sugar-free varieties are also sold.

We are talking about sports drinks, which have been marketed as beverages consistent with a healthy lifestyle. Most popular sports drinks contain between half and two-thirds the amount of sugar found in soda, although sugar-free varieties are also sold.

The researchers found that as students drank more soda, their amount of physical activity and fruit and vegetable consumption decreased. But both physical activity and fruit and vegetable consumption increased as students drank more sweetened fruit beverages other than soda.

They interpret this to mean that drinking sweetened fruit beverages other than soda is considered to be part of a healthy lifestyle. And they attribute this to marketing practices labeling these drinks as healthy.

In other words, people perceive soda as unhealthy, but do not see non-carbonated, sweetened drinks in the same light.

There's a vast array of high-sugar beverages being sold today. They include fruit drinks, fruit punch, lemonade and flavored tea drinks, as well as sports drinks. They're all high in calories. But football players don't dump a vat of fruit punch over the coach's head after a victory. They use a vat of sports drink, usually with a highly visible logo on it. This helps fuel the perceived association between sports drinks, athletes and good health.

The study authors set out to see what behaviors co-existed with drinking sugary beverages. They used data from a state project called SPAN that was designed to monitor childhood obesity and related behaviors. Part of the SPAN project collected information from 15,283 Texas 8th and 11th grade students in 2004 and 2005. The students were asked how many times they drank regular soda yesterday or "any punch, Kool-Aid, sports drinks, or other fruit-flavored drinks," not including fruit juice. The students also filled out questionnaires detailing 22 other dietary behaviors and six measures of physical and sedentary activity.

Sedentary behaviors (hours spent watching TV, using the computer or playing video games) increased as overall sweetened beverage consumption increased. And as students drank more sugary drinks, they also ate more fried foods, meats and desserts. For these behaviors, it did not matter if the sweetened drinks were soda or not.

Roughly 28% of the students reported drinking at least three sugar-sweetened drinks a day.

The researchers point out that drinking just one can of soda or other sugary drink a day could lead to a 10-pound weight gain in a year. They recommend drinking water instead.

For a nation of people with bulging waistlines, making sugary drinks a part of the diet is not healthy. Whether these drinks are soda, fruit drinks or sports drinks is largely a difference of degree. Somehow, the notion that sugary drinks are healthy as long as they aren't soda may have crept into the national consciousness. And it isn't doing anyone any good, except for the drink manufacturers.

An article detailing the study appears in the October 2010 issue of the journal Pediatrics.