There's no question that soft drinks and other sweetened beverages add empty calories to kids' diets, and their widespread consumption is widely believed to be a factor in the obesity epidemic. But if you cut out the soda, will kids compensate for the missed calories by simply eating or drinking more of other things?

That question was among the topics discussed at a session I attended Monday at the annual meeting of the Obesity Society in Phoenix. (Yes, they serve food at the meeting, and no, it's not just vegetables.) Researchers at Columbia University, the Harvard School of Public Health, and Children’s Hospital in Boston analyzed data from nearly 3,100 children ages 2 through 19 in the nationally representative NHANES (National Health and Nutrition Examination Survey) survey, a large, ongoing government study of Americans' dietary behaviors.

They found that for every additional 8-ounce serving of sugar-sweetened beverages—including soft drinks, fruit-flavored drinks, sports beverages, and sweetened iced tea—consumed in a given day, the kids ingested an extra 111 calories compared to days with no sugar-sweetened beverages. But when the kids replaced sweetened beverages with water, they decreased their total caloric intake for the day without a compensatory increase in other food or beverages. In other words: Kids don't seem to miss the extra calories when they drink water instead of soda or other sugar drinks.

CR's Take. Strangely, drinking diet drinks instead of sweetened ones didn't result in the same overall calorie decrease that drinking water did. All of which makes a sound argument for encouraging kids to use good old H2O as their go-to thirst-quencher. It's healthy, it has no calories, and—perhaps best of all in these trying economic times—it's free. To give it some flavor, add a bit of 100 percent fruit juice or strongly brewed, flavored tea; squeeze in half a lemon, lime, or orange; or drop in frozen fruit or ice cubes made from fruit or juice.

Read our earlier coverage on soft drinks and other types of liquid calories.

—Jamie Kopf Hirsh, associate editor

Read our tips on how to keep your child at a healthy weight, and check out our Treatment Ratings (subscribers only) for obesity.