Better research on the impact of smaller plates

An international team of researchers conducted a feeding study (Int J Beh Nutr Phys Act 2019;16:75) at a feeding laboratory specifically designed for their research: a lounge with a dining table and chair, a sofa and bookshelves, and a television showing a nature program.

The 134 adult men and women were served a lunch, presented on a heated serving table in the room, consisting of either a vegetarian cheese and pasta bake or chicken korma curry. The participants were randomly given either a large or small plate and were instructed to serve themselves from the serving dish on the heated table and to consume as much or as little as they wished.

They were given 30 minutes to eat, during which they were filmed with hidden cameras. (The participants were told ahead of time that they would be filmed: the cameras were hidden to minimize self-consciousness on the part of the participants.)

Not only did the authors weigh the amount the participants served themselves, as well as the actual amount consumed, but they also took note of how many times they served themselves, how many minutes the participants spent eating, and how many bites they took (and thus the average size of each bite).

The two test plates were circular, white china plates with no decoration to distract the eye. The large plate was 29 centimeters across (about 11.4 inches), while the small plate was 23 centimeters across (about 9 inches).

After analyzing how much food was consumed, the authors found that "there was no clear evidence of a difference in calories consumed between the plate size groups." Further, the only other measure, from time spent eating to bite size, that was statistically significant between the two groups was how much food was left on the plate: those using the larger plate left about 1/3 ounce more on their plate, uneaten, than those with a smaller plate.

What this means for you

The authors note that using smaller plates is common advice, even from quite reputable sources (including myself). They say, "The current evidence is... insufficiently conclusive to either endorse or refute such advice." Which is not to say, they admit, that this can't be one of several methods, both proven and unproven, that people use to try to control their intake.

What's important here is not the size of the plate, but knowing what is an appropriate portion size. If using a smaller plate helps you feel more satisfied with a smaller portion size than you are used to, by all means, use it. Don't assume, however, that using a smaller plate will automatically mean you are eating less.

First posted: October 16, 2019