Contrary to popular perception, a large proportion of obese Americans can and do lose weight, and the old tried and true methods of eating less fat and exercising are some of the most effective paths to weight-loss success.

"This is great news because studies have shown that even a 5 percent reduction in weight can lead to improved health," says lead author Jacinda M. Nicklas, MD, MPH, MA, a clinical research fellow at Beth Israel Deaconess Medical Center and Harvard Medical School. "With more than a third of Americans now obese and fifty to seventy percent of them trying to lose weight, this is important because the health risks associated with carrying that extra weight are substantial."

Researchers analyzed data from more than 4,000 obese individuals culled from the 2001-2006 National Health and Nutrition Examination Survey conducted by the Centers for Disease Control and Prevention.

"Those who exercised more and ate less fat were significantly more likely to lose weight," say the authors. "Additionally we found a correlation between joining weight loss programs and greater reported weight loss, which may speak to the importance of structure in a weight loss regimen" says Nicklas. And while those who used prescription weight-loss medications also reported weight loss, this represented only a small number of study participants.

In contrast, the authors found that, "self-reported use of popular diets, liquid diets, nonprescription weight loss pills and diet foods/products were not associated with weight loss."

Read more from Beth Israel Deaconess Medical Center/Harvard Medical School.