People writing down what they eat every day lose on average twice as much weight as those who don’t, according to a new study to appear in the August issue of the American Journal of Preventive Medicine.

Victor Stevens senior investigator at Kaiser Permanente Center for Health Research in Portland, Ore. and his colleagues tracked 1,685 men and women who were overweight or obese and having obesity-related problems like high blood pressure. About 44 percent of the participants were black people who are believed to have higher risk for conditions linked to obesity such as type 2 diabetes and heart disease compared to whites.

After a six-month period of follow-up, the researchers discovered that the participants lost on average 12.5 pounds. However, those who managed to keep food diaries six or seven days a week lost about 18 pounds compared to 9 pounds for those not regularly writing down what they ate.

Besides keeping food diaries, the participants kept a healthier diet composed of more fruits, vegetables, and food with less fat, attended weekly group meetings and exercise 30 minutes a day mostly by walking.

“There is a misconception that nobody can lose weight, but in this study, two-thirds of them lost enough weight to make a difference to their health,” Stevens said.

More exactly, losing that amount of weight is enough to improve your cholesterol levels, to lower your blood pressure and the risk of developing diabetes, the researchers noted.

How exactly does the food diary help you? Well, according to the study, keeping food diaries makes you more aware of “where the extra calories are coming from.” Therefore, looking over what you previously wrote down, “you put yourself in a position where you are accountable for your behavior, it changes your behavior.”

As the U.S. confronts itself with an obesity epidemic, the new study comes just at the right time. And, why not say it, the new method seems to be less expensive than other methods you might have tried it.

The study was funded by a grant from the National Heart, Lung, and Blood Institute.