Foods that promote weight gain

By CBS News

How often do you worry that you should cut down on eating certain foods? Fewer than four times a week: 0 points Four times a week or more: 1 point

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Weight gain has more to do with diet than how much exercise a person gets, according to a new study

(CBS/AP) Which foods cause the most weight gain? A new Harvard study holds some big surprises.

For the study - published in Thursday's New England Journal of Medicine - doctors analyzed diet and lifestyle habits of 120, 877 non-obese people. Their weight was measured every four years for 20 years, and they detailed their diets on questionnaires.

On average, participants gained nearly 17 pounds over the 20 years. For each four-year period, food choices contributed to an extra four pounds while exercise cut less than two pounds.

"There is no magic bullet for weight control, " said one study leader, Dr. Frank Hu. "Diet and exercise are important for preventing weight gain, but diet clearly plays a bigger role."

The authors' message? Eat more fruits, vegetables, whole grains and nuts. Cut back on foods that cause weight gain.