New research provides evidence that proposed taxes on soft drinks may make young people healthier.

The study, which collected food intake data from 12,123 young adults for 20 years, found that with every 10 percent increase in the price of a two-liter bottle, people consumed 7 percent fewer calories from soda. They also took in fewer calories over all.

When people faced an even larger increase — $1 for a two-liter bottle of soda, comparable to a proposed tax in Philadelphia — they consumed 124 fewer calories a day, the study found. The lower soda intake was associated with a drop in weight of more than two pounds — and a lower risk for pre-diabetes. The study appears in the March 8 issue of Archives of Internal Medicine.

Maureen L. Storey, senior vice president for science policy at the American Beverage Association, said taxing soda would be discriminatory as well as ineffective. “Taxes do not make people healthier,” she said. “Making smart education decisions about diet and exercise do.”

But the study’s lead author, Barry M. Popkin, an obesity specialist at the Gillings School of Global Public Health at the University of North Carolina, said the study would help answer an important question.

“You always know that if you reduce the cost or increase the cost of something, consumption of that item will change,” Dr. Popkin said. “What we don’t know is whether you will buy something equally bad or worse. In this case, we found that people would get healthier.”  @