In America's battle against obesity, good news has been rather slim. But a new report offers a hint of hope —albeit amid figures confirming that 1 in 3 adults are now obese. The report comes from the National Health and Nutrition Examination Survey (NHANES). Started in 1960, NHANES regularly surveys thousands of Americans to track trends in health, diet, and nutrition, with new statistics published every couple of years. The survey has measured people's weight and height since its launch, allowing researchers to calculate and compare Americans' body mass index (BMI) over time. (Your BMI is a single number that's worked out from your height and weight. It indicates whether you are at a healthy weight, underweight, overweight, or obese.)

Back in the 1960-1962 survey, an estimated 13.4 percent of adults were obese. But in the latest survey, done in 2007-2008, this number was 33.8 percent—a third of all adults. The rise in obesity was particularly steep in the 1980s and 1990s, with some experts predicting that almost half of U.S. adults would be obese by 2020. But here's the glimmer of hope: the new NHANES analysis suggests that obesity rates may actually be leveling off.

Over the 10-year period from 1999-2008, the obesity rate for women held fairly stable, the researchers say. And although the overall rate for men increased during this time, the rate didn't differ significantly in the most recent surveys, done in 2003-2004, 2005-2006, and 2007-2008.