The study by researchers from Children's Hospital Boston comes at a time when soda firms are increasingly coming under attack for selling their products in schools.
The randomized, controlled trial involved around 100 children aged 13 to 18. Half of the children avoided sugar-sweetened beverages, such as sodas, sports drinks, ice teas and lemonades. They received weekly deliveries of non-caloric beverages of their own choosing- bottled waters and artificially-sweetened drinks. The remaining teens, who served as a control group, were asked to continue their usual eating and drinking habits.
The children all received monetary incentive for sticking to the six-month study, as well as regular reminders.
The findings, published in this month's issue of Pediatrics, revealed that the children receiving deliveries reduced their sugary drink consumption by 82 percent and had a "marked decrease" in body mass index (BMI). The control group's intake of sugary drinks remained unchanged, with this group revealing a "slight increase" in BMI.
The group-to-group difference came to almost one pound per month, said the researchers, who calculated that a single 12-oz sugar-sweetened beverage per day translates to about one pound of weight gain over 3 to 4 weeks.
"Sugary beverages have no nutritional value and seem to make a huge contribution to weight gain," said lead researcher Dr Cara Ebbeling.
Comprehensive weight-loss programs often do not have a substantial effect on body weight, she added. "People often get overwhelmed by nutrition advice and give up. We opted to study one simple, potentially high-impact behavior, and made it easy for adolescents to replace sugary drinks with non-caloric beverages."
The study comes at a time of growing concern that sugary soft drinks are contributing greatly to the growing obesity epidemic among children. A recent report showed that sweet drinks have overtaken white bread as the leading source of calories in the American diet, while another suggested that consuming fructose affects the metabolic rate in a way that favors fat storage.
All this has lead to greater pressure on soft drinks manufacturers to address health concerns. There has also been intense lobbying from health groups to kick out soft drinks and junk food from schools in America, and the industry is also due to face a lawsuit aimed at getting soft drinks firms out of US schools on obesity grounds.
But the industry has not remained entirely unresponsive to the attacks. Indeed, last year the American Beverage Asociation (ABA), backed by PepsiCo and Coca-Cola, introduced a voluntary ban on all drinks except water and 100 per cent juice in elementary schools, and all full-calorie soft drinks in middle schools in the US.
"Childhood obesity is a serious problem in the US, and the responsibility for finding common-sense solutions is shared by everyone, including our industry," the ABA's president and chief executive Susan Neely had said.