12/15/2014 12:38 pm ET Updated Feb 14, 2015

Should We Really Shrink Our Plates?

Can eating from a salad plate -- rather than an entrée one -- trick you into eating less? An optical illusion may cause us to misjudge the quantity of food on a plate depending on its size, and our appetite might follow our eyes rather than our stomach. If you ever flip through health and lifestyle magazines you must have already encountered the choose-a-smaller-plate advice dished out almost as fact. 

My personal feeling about this guidance is mixed. 

At the self-serve frozen yogurt shops, that are now as numerous as gas stations, and are tempting me with their theoretically low-calorie treats, the smallest bowl is not at all small, and I do feel like its size pushes my buttons to fill in some more -- a dollop of frozen yogurt looks lonely and unsupported just sitting there, with no walls to hug it. On the other hand, for solids I just love larger plates. I feel like the negative space around the food makes the food look beautiful and precious, and it's much easier to eat politely when there's all this defined territory for cutting and picking up the food. I usually set the table with large plates, and use small ones just for dessert. That's my feeling, and now for some data. 

new review study gathered all the human studies that manipulated plate size and looked at what people ate, and found nine relevant ones. The meta-analysis of these studies, led by Eric Robinson, and published in Obesity Reviews, finds that the widespread small plate recommendation might have been premature. Five studies found that plate size had no effect, one showed mixed results, and three reported significant effects. When you combine all the studies together the effect of plate size is at most really small. Interestingly, the three studies that showed people ate more from larger plates were using bowls rather than plates, and those that showed no difference used plates. It's of course hard to draw definitive conclusions; factors like dining setting, the ability to refill the plate and weight status also have to go into account, but my feeling is that serving a solid in a plate is quite different from serving or liquid in a bowl or even an amorphous food on a plate. A mostly empty bowl isn't appealing, and a larger bowl will mean a bigger serving -- for me at least.

Manipulating the food environment can be a great tool for effortlessly improving people's eating habits, but this analysis suggests cafeterias should await further proof before they overhaul the dishware. When trays were eliminated in college cafeterias in an effort to reduce overeating and waste, the unexpected and inadvertent result might have been that students, lacking a third hand, skipped the salad. Similarly, a small plate might be loaded with the same amount of food, and might also have fewer veggies on it.

Dr. Ayala