Do adults draw differently-sized meals on larger or smaller plates? Examining plate size in a community sample

Highlights

• This study uses a protocol called plate mapping, where people draw a meal on a plate.

• Plate mapping examines how participants conceptualize meal and portion size.

• Meal size sensitivity occurred as participants drew bigger meal areas on larger plates.

• Meal composition sensitivity occurred as participants drew bigger portions on larger plates.

• This study reports findings in a community setting that are similar to studies done in college populations.

Abstract

Background

Prior research has reported that plate size may influence an individual’s perceptions and recall of food and meal size. Therefore, manipulating plate size could influence projected meal quantities and portion size among community dwelling adults.

Methods

The present study interviewed 281 adult parents in their own homes in a medium-sized city in the United States. Participants were asked to accurately draw and label the foods they expected to eat for dinner that night, drawing on either a 23 cm or 28 cm paper plate. The respondents were then asked to label each food drawn in order to ensure proper recording of meals.

Results

Results showed clear differences in drawn food sizes between plate sizes as well as between sexes. Larger plates had about 24% more food drawn on them than small plates. Men drew their meals on 28 cm plates to be 37% larger than men who received 23 cm plates, while women with 28 cm plates drew their meals to be about 17% larger than women given 23 cm plates. Most (60%) of the overall differences in food size between plates came from the biggest food that was drawn. Women and men both drew bigger meat portions on 28 cm plates when compared to the meat portions on 23 cm plates.

Conclusions

Overall, these findings support the concept that adult participants’ estimates of dinner meal size may be shaped by plate size. The effect of differing plate sizes appears to be more powerful for men than women, and may encourage greater food consumption among men, primarily as meat products.

Introduction

People in Western societies usually consume foods grouped on tableware, often plates. The size of plates may influence how much and which types of food a person serves themselves or is served, which subsequently may have an effect on portion size and food type (Hollands et al., 2015). This study examined whether community dwelling adults differently portrayed how much and what types of foods they planned to eat on bigger or smaller plates.

Most studies of the effects of tableware on food selection manipulate plate, bowl, or serving utensil size as individuals serve themselves or are served foods (Hollands et al., 2015, Fisher et al., 2013, Peng et al., 2017, Raynor and Wing, 2007, Robinson et al., 2014). An alternative research technique, labeled “plate-mapping,” (Sharp & Sobal, 2012) has individuals draw a meal on differently-sized plates.

In an initial study using plate mapping (Sharp & Sobal, 2012), researchers asked college students to draw a meal on either a 23 cm or 28 cm diameter paper plate. The findings revealed that students exhibited plate size sensitivity because they drew about 26% more food on the larger plate than students given the smaller plate. The larger plates had about 50% more available space to draw upon, which made the food drawings on the larger plates appear smaller when observed within the context of the plate. The sex of these students moderated the relationship between plate size and meal composition in that initial study as indicated by the size of food types, with women drawing 36% bigger vegetable portions than men on larger plates. This plate mapping measurement method has been subsequently validated through objectively measured behavior in a college student sample (Sharp, 2016). Participants were approached directly before or directly after the consumption of a meal at a college cafeteria and asked to either draw the meal that they were about to consume or draw the meal that they had just consumed. Paper plates 23 cm in diameter that were identical to the size of the plates used in the cafeteria and larger 28 cm plates were randomly distributed to participants to use in drawing their meals. Results from this study showed that these participants were able to draw the sizes of their food items with a high degree of accuracy prior to consuming as well as after consuming a meal on both sizes of plates.

Prior studies of the size of dishware and intake of food had mixed findings and were conducted from samples of college students and patients in medical facilities. Some of these studies observed no difference in energy intake between those using larger and smaller dishware (Rolls et al., 2007, Shah et al., 2011) while other studies report an interaction between plate size and portion size (Koh and Pliner, 2009, Ahn et al., 2010, DiSantis et al., 2013, Fisher et al., 2013). These prior studies of plate size and food intake conducted in college or medical settings, while providing more control over the variables being tested, may not have ecological validity to generalize their findings to households or realistic eating situations of community dwelling adults (Henreich et al., 2010, Werthmann et al., 2015, Wang et al., 2018).

The present study used plate mapping to examine plate sensitivity and meal composition in the homes of an adult population whose behaviors may be differently shaped by their experiences, home environments, and family roles than college students. Using a plate mapping protocol in an adult community sample is important for both proof of concept of plate size sensitivity and generalizability of findings into households where the broader population usually eats. This lack of generalizability is due to the college environments being more homogenous than the environments of nonstudent subjects (Peterson, 2001) and not necessarily representing domestic practices or behaviors that will be continued past graduation (Cooper, McCord, & Socha, 2011). Adults' cooking skills, financial resources, time availability, and interactions with other family members are all part of the external environment involved in food selection that may be associated with meal composition and serving portions of each type of food.

We propose four hypotheses about plate sizes and plate mapping. 1) The plate sensitivity hypothesis posits that people are flexible with portion sizes (Haynes et al., 2019) and fill plates according to how much food they can hold, drawing bigger overall meal sizes on larger plates than they would on smaller plates. 2) The meal norms hypothesis posits that people draw meals to conform to normative social conceptions about how full a plate should be; filling plates to levels that seem appropriate to the plate size, with the same percentage of area covered by food on larger and smaller plates. 3) The meal composition hypothesis posits that plate size influences serving of different kinds of foods, with the type of food sub-hypothesis proposing that bigger vegetable dishes will be drawn on larger plates than smaller plates, and the food course sub-hypothesis proposing that bigger main courses will be drawn on larger plates than smaller plates. 4) The sex moderation hypothesis posits that differences between sexes in food selection and size (Emanuel et al., 2012, Rolls et al., 1991, Wardle et al., 2004) occur in plate size effects upon food choice, with men more sensitive to plate size than are women, and men drawing larger main courses on plates than women draw on plates.