Losing weight and keeping it off is a common goal—and constant challenge—for millions of Americans. And people spend loads of cash on specialized diet and weight loss programs, meetings, even personal coaches. But could something as easy, accessible and affordable as an online program help people trim down?

With the rising rates of people who are overweight or obese, researchers have been trying to find cost-effective ways to help more people lose more weight—more easily. A new review of 18 randomized studies finds that computer-based and online programs do, indeed, help people who are overweight or obese drop weight and maintain that progress. The 143-page analysis, which assessed data from 4,140 adults, was published online this week in the Cochrane Library.

After following a computer or online weight-loss program for six months, participants in various studies shed more pounds than those who received more basic care, such as a paper workbook or pamphlet. Individuals who were in weight-maintenance programs that used computer-guided tools also kept weight off better than those who got the basic care. The online programs often included interactive features, message boards and messaging capabilities. Although there were variances in how long the studies followed subjects, the review authors were able to conclude that, "Computer-based interventions have a positive effect on short-term weight loss and short-term weight loss maintenance."

Some of the studies also included a group of subjects who were placed in-person weight-loss programs, such as weekly or monthly meetings. Those individuals tended to lose the most weight overall. "But health care providers have limited opportunities to provide this care," said Susan Wieland, of the University of Maryland School of Medicine in Baltimore, and lead-author of the analysis, in a prepared statement. Finding a less labor- and resource-intensive way to help more people lose weight—even if that weight loss is only moderate—could make a big difference on the national or global scale.

"These large-scale systematic reviews are helpful to determine—using available peer-reviewed studies—what works and what doesn't work," noted Karina Davidson, director of the Center for Behavioral Cardiovascular Health at Columbia University Medical Center and study co-author, in a prepared statement. With the new findings, "health care providers can make evidence-based recommendations," she said—especially "since more patients are participating in online weight loss or management programs." The new review did not include smartphone or tablet-based apps, but the researchers hope to include studies of those when they update the review in the future.

With 1.5 billion people worldwide expected to be overweight or obese in 2015—just a year and a half from now—the global burden of related, preventable health problems, such as diabetes, heart disease and stroke, is expected to continue rising. In the U.S., obesity is already a taking a bigger toll on health than smoking. The latest results suggest that simply logging to an interactive program could help many more people spare themselves the weight as well as future medical trouble.