The so-called "obesity epidemic" has been topping headlines everywhere this year, and a new study endeavors to find out why so many U.S. adults are overweight. The proportion of obese adults in the United States has doubled since 1970, and today, a third of all adults in the US are overweight. This frightening statistic has prompted experts to look into the causes of this unbridled weight gain, and a new study shows that reducing snacking may be the key to losing weight.

In the study, published in the journal PLoS Medicine, experts analyzed food data from individuals over the last 30 years to determine the cause of our higher levels of caloric intake today. The average person in 1977-1978 consumed about 1,803 calories every day, whereas in 2003-2006, the average person consumed 2,374 calories daily. The researchers wanted to find out which factors were the most significant in increasing the number of calories we consume every day.

The results of the study showed that people today, in comparison to consumers in 1977-1978, indulge in a greater number of "eating occasions" and have larger portion sizes, two factors which account for most of the increase in caloric intake over the past 30 years. Although portion sizes have increased by 12%, it is the frequency of eating that seems to be the main factor driving weight gain.

In a report by Health.com, the main author of the study, Barry Popkin Ph.D., explains that in addition to three meals a day, many people are now snacking almost constantly throughout the day, consuming large quantities of junk food that is filled with fat, salt, and sugar. Popkin has found that the amount of time between snacks and meals has decreased dramatically in comparison to consumption in 1977, and that calorie intake from snacks has increased significantly. Popkin says that due to food advertising, consumers are faced with processed snack food everywhere, all the time, and that the ubiquity of snack food encourages consumers to be munching constantly. The authors conclude that efforts to reduce the obesity rate should focus on decreasing the frequency of snacks and meals throughout the day.

The good news is that keeping track of the number of snacks you eat every day is relatively simple compared to other weight loss methods (such as counting calories). If you believe that your snacking may be contributing to weight gain, consider keeping a food journal in which you record all of your meals and snacks for a week. Resolve to cut out unhealthy snacks, and remove processed snacks from the house to avoid being tempted. Eat three regular meals a day, punctuated with healthy snacks such as fruits and vegetables. For meals, consulting a food guide, such as the new MyPlate icon, can help you to prepare meals with healthy proportions of fruits, vegetables, grains and proteins.