Adults Only: Why Don't Children Belong to the Clean Plate Club?

Abstract

What percentage of the food you serve do you eat? If we could provide estimates of how much food people took they actually ate, this would open the door for a huge number of studies in in psychology, marketing, economics, and consumer behavior that have been dismissed or overlooked by nutrition and public health because they measured how much subjects served, but not how much they ate. Providing this eaten estimate was the objective of Wansink and Johnson. After aggregating results from a wide number of self-served meals and snacks, one conclusion was that most adults are members of the clean plate club. Regardless of their sex or ethnicity, it was estimated the average adult in these studies ate approximately 92% (unweighted by sample size) of what they served.In a thoughtful critique of this figure, Robinson et al raise excellent points that suggest this 92% figure is an upper bound, and perhaps even an overestimate of the actual percentage of self-served food a person consumes. One of their points is that many of these studies were lab-based studies where people knew they were being observed and may have acted differently in real life – perhaps serving more and eating less of it with the variation of plate size or perhaps by being less self conscious about serving a second or third helping.What also needs more examination and exploration is the somewhat contrary result that adults consumed a much greater percent of what they served than children. That is, while adults ate between 88.7% (when weighted by study sample sizes) and 92% (when averaged across studies), children (mostly elementary school aged) only ate an average of 59% of what they served themselves. Part of this could be explained these 326 children perhaps 1) not being aware of how hungry they are, 2) not being well-calibrated to know how much food would fill them up, 3) not knowing how much they will like a particularly new food, or 4) not ignoring their internal cues of satiety. This can also vary depending on whether the children are eating their food with utensils or with their hands, whether they are with friends, and whether they are extroverted or introverted.Robinson, et al’s excellent point about context is again relevant in our estimate that children eat only 59% of what they self-serve. Each of six studies used to arrive at this 59% figure were studies where children were not eating in the presence of their parents. Perhaps in the presence of their parents, this number is notably higher. Yet to a loving, but frustrated parent who wants their non-cooperating child to be a vegetable-eating member of the clean plate club, these lab results provide a powerful hidden value. They show that a child who only eats half to two-thirds of the food they serve themselves isn’t being wasteful, belligerent, or disrespectful. They are just being normal children. This should provide comfort and reduced anxiety for frustrated clean plate club parents.