After age 30, Americans gain about a pound a year and that is one of the reasons obesity is a huge problem in our country. If you had to guess what the number one culprit, what would you say?

Researchers say the biggest culprit is potato chips. Bigger than soda, candy and ice cream. What is the appeal of the chip.....Researchers say chips are tasty and they have a very good texture and people don't eat just a couple of chips, we eat the whole bag. What we eat and how much of it we consume has far more impact than exercise and most other habits do on long-term weight gain, according to the study by Harvard University scientists. Two-thirds of American adults are overweight or obese. The clear message in the study: Eat more fruits, vegetables, whole grains and nuts. Cut back on potatoes, red meat, sweets and soda. "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." Doctors analyzed changes in diet and lifestyle habits of 120,877 people from three long-running medical studies. All were health professionals and not obese at the start. Their weight was measured every four years for up to two decades, and they detailed their diet on questionnaires. On average, participants gained nearly 17 pounds over the 20-year period. For each four-year period, food choices contributed nearly 4 pounds. Exercise, for those who did it, cut less than 2 pounds.

Each daily serving of potato chips contains 1 ounce (about 15 chips and 160 calories) led to a 1.69-pound uptick over four years. That's compared to sweets and desserts, which added 0.41 pound. For starchy potatoes other than chips, the gain was 1.28 pounds. Soda added a pound over four years. Eating more fruits and vegetables and other unprocessed foods led to less weight gain, probably because they are fiber-rich and make people feel fuller. For each four-year period, these factors had these effects on weight:
— An alcoholic drink a day, 0.41-pound increase.
— Watching an hour of TV a day, 0.31-pound increase.
— Recently quitting smoking, 5-pound increase.
People who slept more or less than six to eight hours a night gained more weight.
The study was funded by the National Institutes of Health and a foundation. Several researchers reported receiving fees from drug and nutrition companies.