If you want to lose weight, doing something as simple as recording what you eat might make the biggest difference. Writing down what you eat can double your weight loss, according to a study that the American Journal of Preventative Medicine will publish next month.

This finding comes from an analysis of the first phase of one of the largest weight loss maintenance trials every conducted. After about six months, the nearly 1,700 participants lost an average of 13 pounds.

Kaiser Permanente's Center for Health Research in Portland, Oregon, which ran the study, asked journalists not to write about it until today. But Kaiser Permanente sent me a copy of the forthcoming report, "Weight Loss During the Intensive Intervention Phase of the Weight-Loss Maintenance Trial." And last week one of the study's researchers spoke with me for an hour. The Kaiser Permanente investigators wanted to help a large proportion of people to lose weight and to keep that weight off long-term. The primary purpose of the study was to look at different strategies for long-term weight loss.

Senior Investigator and co-author of the study, Victor J. Stevens, Ph.D., told me that they found that the more food records that the people in the study kept the more weight they lost. The study focused on reducing calories and didn't address the advantages of a low-carbohydrate diet, he said.

"We asked them to write down everything that they ate and drank that had any calories in it," he told me. Dr. Stevens and his staff provided calorie guides and asked the participants to show their records to the investigators and talk about them in regular group meetings.

"Just writing everything down tends to change what people do," he says. "And other people looking at the food diaries tends to make that effect even stronger."

More than two-thirds of all Americans and 85 percent of those of us with diabetes are overweight or obese. "If we all lost as much as the people in this study did, our nation would see vast decreases in diabetes, hypertension, high cholesterol, heart disease, and stroke," Dr. Stevens says.

"One of the myths in common knowledge is that most people can't lose weight," he told me. "That's not been my experience doing weight loss work with many people, and it was not our experience in this study. I see people all the time who are discouraged and don't want to try because they've been told that there's nothing you can do about it. But that's just not the case."

I asked Dr. Stevens to share the food diary form that they developed for the people in their study, and I got it yesterday. While I'm not trying to lose any more weight, keeping it off for the rest of my life is important to me.

So I have started to use this form to record everything I eat. In addition to counting my calories, I am using it limit my carbs, rather than record the fruits and vegetables, low-fat dairy, and sodium that they asked people in the study to track.

You can also use the form to help yourself count your calories while making those adjustments to the form that are important to you. Dr. Stevens gave me permission to make it available to you on my website. It's online at http://www.mendosa.com/kaiser_diary.pdf