April 10, 2012 -- Here's what doesn't really work well if you want to lose weight: "diet" foods, non-prescription weight loss supplements, and liquid or fad diets.

So what does work? Eat less fat, get more exercise, join a weight loss program, and ask your doctor about prescription weight loss pills.

It may seem boring, even a bit old-fashioned. But it works, says a new study in the April 10 issue of the American Journal of Preventive Medicine.

The study set out to find out what successful dieters are doing to shed unwanted pounds and keep them off.

"People actually are losing 5% to 10% of their body weight or more using tried-and-true methods," says study author Jacinda M. Nicklas, MD, MPH. She is a clinical research fellow at Beth Israel Deaconess Medical Center in Boston.

The study included information on more than 4,000 obese people who took part in the National Health and Nutrition Examination Survey. Of these, 63% said they had tried to lose weight. Forty percent said they lost 5% or more of their body weight, and 20% said they lost 10% or more of their excess body weight.