But students can feel the gain without looking at studies.

Allie Lewin, 18, a freshman at the University of Michigan in Ann Arbor, hasn't stepped on the scales recently, but she's afraid that she has gained about 5 pounds during her first two months at college.

Eunice Eun, 18, a sophomore at Brown University in Providence, packed on 15 pounds the first semester of her freshman year. "It was really startling for my parents when I went back home for Thanksgiving break," she recalls.

She blames "the novelty of having the freedom to eat whatever and whenever I wanted."

Nutritionists say that freedom is the undoing of many freshman waistlines.

"Students need to be vigilant," says Lloyd-Richardson. She believes many factors contribute to the problem, including increased alcohol consumption, eating while socializing, decreased physical activity and exposure to high-calorie, high-fat foods everywhere.

TASTING FREEDOM

At many dining halls, students have carte blanche on how much they can eat. "They could conceivably eat a trough of food at any given meal," notes Leslie Bonci, director of sports nutrition at the University of Pittsburgh Medical Center.

"Nobody at home is cooking like a dining hall. They don't have five different entrees and five different desserts at home," she says. "And we know that the more variety people are offered, the more they eat."

Many college cafeterias offer stir-fry entrees, sushi bars, deli counters, sandwich-wrap stations and ethnic foods. They serve hamburgers, fries and pizza. Some have buffets of cereal, frozen yogurt, ice cream and dessert. Then there's the limitless soda and other drinks.

Then there's all that munching when they drink alcoholic beverages, she says. "I tell students if they go out and drink, chances are they are not going to eat a salad. The closest thing they are going to get to a vegetable is the celery stick in the Bloody Mary."

Many are often blindsided by the weight gain. They might overeat for a couple of months before they notice it, and then all of a sudden their pants aren't fitting anymore, and they know they have to stop, Bonci says. "They say, 'How unfair is this? How can this have happened to me?' "

Ann Litt, a registered dietitian in Bethesda, Md., starts getting calls around Thanksgiving from overweight college students. Most blame the food service, but that's only part of the problem, she says.

Students often have hectic, irregular schedules, and they are grazing instead of sitting for regular meals, she says.

"It's dish-and-dash," Litt says. "They walk into the cafeteria and grab some cereal or a bag of something and eat it as they're walking to class."

Some have open boxes of cereal, chips, cookies and pretzels on their desks and frequently reach in for another handful of food while they're studying. Before they know it, they've consumed 600 to 800 calories, says Litt, who visited the cafeterias of 70 colleges for the second edition of her book, "The College Student's Guide to Eating Well on Campus."

This confluence of foods comes at a time of great change, she notes. "A lot of kids eat because they are sad, lonely, bored. Food is a friend. It's comforting."

Lewin says she has been trying hard not to gain. At the dining hall, she limits herself to salads with light dressing and turkey sandwiches with no mayo. But she gets really hungry late at night when she's studying and noshes on granola bars and chocolate.

Eun also indulged in late-night snacking. "I lived steps away from a late-night eatery, and my friends would go there and get pizza."

The smorgasbord of choices was overwhelming. "I'm Korean, and we eat a lot of rice, vegetables and fish," she says. "I wasn't used to this buffet-style American food available to me at any time I wanted."

It took Eun eight months to lose the weight. She went back to eating more vegetables and fish and exercised religiously. She now weighs 128 pounds at 5 feet 6 and runs almost daily.

TIME FOR EXERCISE

For many freshmen, old exercise habits fall by the wayside. Lewin played soccer year-round in high school and now is on an intramural team that practices only once a week. It's hard to get motivated to go to the gym, which is outdated and hot, she says.

At 5 feet 1, she believes she now weighs about 115 pounds, up from 110. But she's determined to nip the increase in the bud. "I'm going to have to force myself to go to the gym every other day and not snack between meals."

One of the most valuable things college students can do is to establish a meal schedule right along with their class schedule each semester, says registered dietitian Robyn Flipse, author of "Fighting the Freshman Fifteen."

"It doesn't matter if the meal times don't conform to the traditional times. What matters is that there are three opportunities built into each day to sit down and eat a meal," she says.