11/20/2013 03:22 pm ET Updated Jan 25, 2014

No Tray, No Salad

Students load their trays in all-you-can-eat cafeterias with heaps of food, leading to waste and perhaps also to overeating. In an effort to save food, many cafeterias in higher education nationwide have gone trayless.

This sounds like a clever green move: no tray to wash, and according to Aramark's research, removing trays reduces food waste by 30 percent.

But what does tray disappearance do to food choices? With just two hands, what do students leave behind?

No room for salad
A new study by Brian Wansink and David Just, published online ahead of press in Public Health Nutrition, looked at what 417 students ate at a college cafeteria on two Tuesday evenings with identical menus: in one of the meals trays were available, and in the other they were not. The researchers noted whether the students took salad or dessert with their entrée, and the amount of food left in the plates once cleared.

And the results: On trayless day the percent of salad takers decreased by 65 percent, while the proportion of students taking dessert remained about the same.

Apparently, if one hand is holding an entrée, the other one tends to reach for dessert.

The researchers found that trayless diners did not necessarily clean their plates -- they actually threw away a little more of their entrée and dessert, but not of their salad.

So this study doesn't confirm that ditching trays reduces waste, but it does raise the concern that eliminating the tray affects food choices, and not for the better.

So how can we reduce waste and maintain healthy choices? Wansink and Just suggest experimenting with smaller trays or lining trays with "waste not" decals as options worth exploring.

Dr. Ayala