PORTLAND, OR -- Something as simple as keeping a food diary can double a person's weight loss, according to a new study.

“The more food records people kept, the more weight they lost,” says lead author Jack Hollis, a researcher at Kaiser Permanente's Center for Health Research in Portland, OR. “Those who kept daily food records lost twice as much weight as those who kept no records. It seems that the simple act of writing down what you eat encourages people to consume fewer calories.”

In addition to keeping food diaries and turning them in at weekly support group meetings, participants were asked to follow a diet rich in fruits and vegetables and low-fat or non-fat dairy, attend weekly group sessions, and exercise at moderate intensity levels for at least 30 minutes a day. After six months, the average weight loss among the nearly 1,700 participants was approximately 13 pounds. More than two-thirds of the participants (69 percent) lost at least nine pounds, enough to reduce their health risks and qualify for the second phase of the study, which lasted 30 months and tested strategies for maintaining the weight loss.

This is one of the few studies to recruit a large percentage of African-Americans as study participants (44 percent). African-Americans have a higher risk of conditions that are aggravated by being overweight, including diabetes and heart disease. In this study, the majority of African-American participants lost at least nine pounds of weight, which is higher than in previous studies.

“More than two-thirds of Americans are overweight or obese. If we all lost just nine pounds, like the majority of people in this study did, our nation would see vast decreases in hypertension, high cholesterol, diabetes, heart disease and stroke,” says study co-author Victor Stevens. In an earlier study, Stevens found that losing as little as five pounds can reduce the risk of developing high blood pressure by 20 percent.

The findings will be published in the August issue of the American Journal of Preventive Medicine. The research was funded by the National Heart, Lung and Blood Institute at the National Institutes of Health.