When Virginia Tech's largest dining hall reopened several years ago, some administrators jokingly dubbed it the "freshman 25" cafeteria, for the number of pounds some students might gain from the tasty fare.

Students loaded their trays with Belgian waffles, brick-oven-baked pizza, falafel, Brazilian skewered meat, pad Thai, fruit juice concoctions and elaborate desserts - so much food that even the biggest of guys with the biggest of appetites could not always clean their plates.

As food service workers watched thousands of pounds of food go to waste, the university decided to make a move increasingly common at higher-education institutions nationwide: It got rid of cafeteria trays.

The change was immediate. "The plates were coming back basically cleaned," said Ted J. Faulkner, Tech's senior associate director of housing and dining services. "It was astounding."

Most schools in the Washington region have gone "trayless" in at least one dining hall, and several nationwide have banned them altogether.

But perhaps inevitably, there has been a backlash - in part because cafeteria trays had alternative lives as sleds and collegiate souvenirs. When the University of Massachusetts at Amherst got rid of trays in several dining halls last academic year, a group of students formed a "Bring back the trays" Facebook group. One argument posted on the group wall: "What will we use for sleds now?"

Without a tray, students have to be pickier during the first sweep of the cafeteria line and make trips back for more. It results in as much as 25 to 30 percent less wasted food, according to a 2008 study of 25 campuses by food services provider Aramark.

"It's a better pace. You have to get up and walk it off" in between courses, said Cody Erickson, 20, a junior horticulture major from Sandy Spring, sitting with a small pile of cleaned-off lunch plates in Virginia Tech's D2 dining hall last week.

Going trayless is usually sold to students as an environmental move. Less water, soap and electrity is used if there are no trays to wash, and less food is wasted.

Among those that have completely ditched trays are Georgetown, Johns Hopkins, James Madison and Marymount universities and the University of Virginia. Trinity Washington University has "trayless Tuesdays and Thursdays," and the University of Richmond skipped the alliteration with its "trayless Fridays."

American University banished trays from its main dining hall in 2009 after a group of students wrote a paper proposing the move. They called it "Dude, Where Is My Tray?"

Shenandoah University in Winchester, Va., went trayless in 2007 and sold its 600 red cafeteria trays for $2 as a fundraiser for campus sustainability programs. At the University of Mary Washington, officials replaced large trays with smaller ones before phasing trays out altogether last year. St. Mary's College of Maryland went trayless a few years ago, and students there use reusable to-go containers.