By Joene Hendry

NEW YORK - Studies reporting a link between sugar-sweetened beverages and weight gain have garnered a lot of attention but actually research on the issue has yielded mixed results, researchers note in a new report.

"The purported link between soft drinks and other beverages and obesity risk is unclear and complicated, especially in youth," Dr. Mark A. Pereira, at the University of Minnesota in Minneapolis and an author on the report, told Reuters Health.

In a study Pereira and colleagues conducted, they found no link between weight gain over 5 years and teens' drinking of sugar-sweetened beverages.

According to report in the American Journal of Clinical Nutrition, Pereira's team assessed diet, lifestyle, and weight in 2,294 ethnically-diverse boys and girls in the Minneapolis/St. Paul school system.

Initially, when the teens were about 15 years old, 1,289 reported drinking 7 or more servings of white milk weekly, while 1,456 said they drank sugar-sweetened punch and 1,325 said they drank sugary soft drinks up to 6 times a week. Additionally, about 1,300 of these teens said they drank up to 6 servings of apple juice or orange juice weekly.

The investigators saw no overall association between consumption of sweetened beverages and the teens' weight gain over 5 years after allowing for other behaviors tied to beverage drinking habits and weight status.

However, Pereira and colleagues found drinking little or no white milk tied to greater gains in body mass index (BMI); while drinking white milk nearly every day or more often seemed tied to lesser BMI gains. BMI -- calculated by dividing weight in kilograms by height in meters squared -- is a standard way to determine how fat or thin a person is.

Their findings also showed an association between diet soft drink intake and greater weight gain, but this finding "appeared to be explained by overall dieting practices," rather than diet soda drinking, Pereira noted.

The link between sugar-sweetened beverages and obesity risk in youth may be "weaker than we have been led to believe by individual high-profile studies," Pereira said. For clarity on this topic, his group suggests further large-scale, well-conducted investigations.