It's not just unhealthy teens who are drinking high-calorie, sugar-sweetened drinks, new research finds; healthy kids drink them too, but often in the form of sports drinks.

The research suggests that even healthy teens – those teenagers who like to exercise and eat their fruits and vegetables – get confused by the marketing of sports drinks and interpret them to be healthy drinks.

The new study, from researchers at Michael & Susan Dell Center for Healthy Living at the University of Texas School of Public Health in Austin, surveyed more than 15,000 middle and high school students throughout Texas.

They asked the teens – about 20 per cent of whom were obese -- about their eating habits and drink preferences. They also asked about their activity levels and time spent in front of the TV or computer.

They found that teens who drank sugar-sweetened beverages, including sports drinks, were more likely than kids who didn't drinks sweetened drinks to eat unhealthy foods and watch more TV.

That finding wasn't altogether a surprise. What was surprising was that students who drank sports drinks were more likely than pop drinkers to exercise and eat fruits, vegetables and milk.

The study authors says that finding suggests that the teens viewed sports drinks as healthy or acceptable in a healthy lifestyle – even though the drinks are still high in calories.

"The most likely explanation for these findings is that [flavoured sports drinks] have been successfully marketed as beverages consistent with a healthy lifestyle, to set them apart from sodas," the authors write in this week's edition of Pediatrics.

"Often, these beverages contain a minimal percentage of fruit juice or, more commonly, contain artificial fruit flavors, which conveys the impression that the drink is more healthful than it actually is.

They also found that the level of physical activity increased with the amount of sports drinks consumed, but fell with the amount of pop they consumed.

The results are important, given that the researchers found that 83 per cent of boys and 78 per cent of girls drank one or more sugar-sweetened beverage the previous day – with 28 per cent of them drinking three or more pops or sports drinks a day.

The authors note that it is disturbing how many sweetened drinks teens are drinking, given that research suggested that drinking just one soft drink can a day could lead to as much as a 15-lb weight gain in one year.

They say that understanding who drinks what kind of drink will help to better inform policy makers as they work on public health campaigns and other interventions.