Contrary to popular belief, most college students don't gain anywhere near 15 pounds during their freshman year, according to a new nationwide study.

Rather than adding "the freshman 15," as it is commonly called, the average student gains between about 2.5 and 3.5 pounds during the first year of college.

And college has little to do with the weight gain, the study revealed. The typical freshman only gains about a half-pound more than a same-age person who didn't go to college.

"The 'freshman 15' is a media myth," said Jay Zagorsky, co-author of the study and research scientist at Ohio State University's Center for Human Resource Research.

"Most students don't gain large amounts of weight. And it is not college that leads to weight gain  it is becoming a young adult."

The results suggest that media reporting of the freshman 15 myth may have serious implications.

"Repeated use of the phrase 'the freshman 15,' even if it is being used just as a catchy, alliterative figure of speech, may contribute to the perception of being overweight, especially among young women," Zagorsky said.

"Weight gain should not be a primary concern for students going off to college."

Zagorsky conducted the study with Patricia Smith of the University of Michigan-Dearborn. The study will appear in the December 2011 issue of the journal Social Science Quarterly.

The study uses data from 7,418 young people from around the country who participated in the National Longitudinal Survey of Youth 1997. The NLSY97 interviewed people between the ages of 13 and 17 in 1997 and then interviewed the same people each year since then. The NLSY is conducted by Ohio State's Center for Human Resource Research for the U.S. Bureau of Labor Statistics.

Among many other questions, respondents were asked their weight and college status each year.

Other studies have shown that college students tend to underestimate their weight by half a pound to 3 pounds. But if people are consistent in underestimating their weight from year to year, it would not impact these results, Zagorsky said.

The study found that women gained an average of 2.4 pounds during their freshman year, while men gained an average of 3.4 pounds. No more than 10 percent of college freshman gained 15 pounds or more -- and a quarter of freshman reported actually losing weight during their first year.

"It's worth noting that while there's this focus on weight gain among freshman, we found that one in four actually lost weight," Zagorsky said.

The researchers examined a variety of factors that may be associated with freshman weight gain, including whether they lived in a dormitory, went to school full or part time, pursued a two-year or four-year degree, went to a private or public institution, or was a heavy drinker of alcohol (consuming six or more drinks on at least four days per month.)

None of these factors made a significant difference on weight gain, except for heavy drinking. Even then, those who were heavy drinkers gained less than a pound more than students who did not drink at that level.

Zagorsky said it was particularly significant that dorm living did not add to weight gain, since one hypothesis has been that the dorm environment encourages weight gain during the freshman year.

"There has been concern that access to all-you-can-eat cafeterias and abundant fast food choices, with no parental oversight, may lead to weight gain, but that doesn't seem to hold true for most students," he said.

The results do show, however, that college students do gain weight steadily over their college years.

The typical woman gains between seven and nine pounds, while men gain between 12 and 13 pounds.

"Not only is there not a 'freshman 15,' there doesn't appear to be even a 'college 15' for most students," Zagorsky said.

Over the course of the entire college career, students who both worked and attended college gained an extra one-fifth of a pound for each week they worked.

The researchers also examined what happened to college students' weight after they graduated. They found that in the first four years after college, the typical respondent gained another 1.5 pounds per year.

"College students don't face an elevated risk of obesity because they gain a large amount of weight during their freshman year," Zagorsky said.

"Instead, they have moderate but steady weight gain throughout early adulthood. Anyone who gains 1.5 pounds every year will become obese over time, no matter their initial weight."

Although most students don't need to worry about large weight gains their freshman year, Zagorsky said they still should focus on a healthy lifestyle.

"Students should begin developing the habit of eating healthy foods and exercising regularly. Those habits will help them throughout their lives."