The "Freshman 15" is more like 5 to 7, but it is followed by the "Sophomore 2 or 3," say researchers who led two of the largest and longest studies ever done of weight gain among college students.
The research also showed that males piled on significantly more pounds than females.
Doctors say it is good news that the number of pounds gained is less than the widely believed 15, but bad news that "Generation XL" kids seem to be learning patterns of gradual weight gain that could spell trouble way beyond graduation.
"It may be 10 or 8, but it continues. That, to me, is a bigger problem," said Rena Wing, a psychologist and director of the weight control center at Brown University Medical School in Providence, R.I.
She and others at Brown reported the studies Sunday at a meeting of the Obesity Society in Boston.
Previous studies were small, looked at weight gain only in the first semester, and involved hardly any male students. The two new studies fill those gaps.
The first, funded by the federal government, involved 382 students — 40 percent of them male — at an unidentified private school in the Northeast. Weight was measured four times — at the beginning of the school year in September, at the end of the first semester in December, after the holiday break in January, and at the end of the freshman year in May.
"Over the year, we found that males gained 5.6 pounds and females gained 3.6 pounds, with the large majority of that weight gained in the first semester," said Elizabeth Lloyd-Richardson, the Brown researcher who led both studies.
One out of six gained 10 or more pounds during freshman year, and 6 percent gained the "Freshman 15" or more.
Men tended to gain weight sharply in the first semester and then more gradually after that, while women gained a lot at first and then tended to plateau, she said.
At the end of the freshman year, more than 17 percent were overweight or obese, compared to only 14 percent at the start.
The second study involved 907 students, 55 percent of them male, at an unidentified public university in the Midwest and was funded by the Robert Wood Johnson Foundation. Students were weighed four times as in the previous study, but also at the end of their sophomore year.
Similar to the first study, students gained an average of 7.8 pounds during the freshman year. More than one-third gained 10 pounds or more, and one-fifth piled on 15 or more.
Things got worse the next year. Males were on average 9.5 pounds heavier, and females, 9.2 pounds heavier, than when they started college.
"Students don't appear to be losing weight over this time and in fact they gained additional weight in their sophomore year," Lloyd-Richardson said.
No one knows why, but the researchers are continuing their study to try to find out. Possible explanations include more drinking (alcohol contains calories), more socializing that involves eating, high-fat foods in dorm cafeterias and less physical activity, the researchers said.
"Something about the freshman year and the sophomore year is putting these kids at risk," said Thomas Wadden, president of the Obesity Society and director of the Center for Weight and Eating Disorders at the University of Pennsylvania School of Medicine.
"I suspect part of this is they now have access to large amounts of food they can eat freely," without anyone at home saying enough is enough, he said.