Empty plates and larger waists: a cross-sectional study of factors associated with plate clearing habits and body weight

Human nutritional intelligence underestimated? Exposing sensitivities to food composition in everyday dietary decisions

The social and cultural significance of food is woven into every aspect of our dietary behaviour, and it contributes to our complex interaction with food. To find order within this complexity scientists often look for dietary 'universals' - phenomena or basic principles that guide our food choice and meal size, irrespective of wider context. One such idea is that taste characteristics provide a signal for dietary composition (e.g., sweet taste signals carbohydrate). Others have suggested that behaviour is guided by learning and is based on associations that form between the flavour of a food and its post-ingestive effects. Despite a large body of research, evidence supporting both processes is equivocal, leading some to conclude that humans are largely indifferent to food composition. Here, we argue that human abilities to gauge the nutritional composition or value of food have been underestimated, and that they can be exposed by embracing alternative methods, including cross-cultural comparisons, large nutrition surveys, and the use of virtual portion-selection tools. Our group has focused on assessments of food choice and expected satiety, and how comparisons across everyday foods can reveal non-linear relationships with food energy density, and even the potential for sensitivity to micronutrient composition. We suggest that these abilities might reflect a complex form of social learning, in which flavour-nutrient associations are not only formed but communicated and amplified across individuals in the form of a cuisine. Thus, rather than disregarding sociocultural influences as extraneous, we might reimagine their role as central to a process that creates and imbues a 'collective dietary wisdom.' In turn, this raises questions about whether rapid dietary, technological, and cultural change disrupts a fundamental process, such that it no longer guarantees a 'nutritional intelligence' that confers benefits for health.

On the measurement and correlates of plate clearing: examining a German version of the Plate Clearing Tendency Scale

PURPOSE

Plate clearing-eating a meal in its entirety-is common and may be a factor contributing to obesity. For the assessment of individual differences in plate clearing tendencies, Robinson et al. (Obesity 23:301-304, 2015) developed the Plate Clearing Tendency Scale (PCTS). However, little is known about the psychometric properties of this scale and its correlates.

METHODS

In the current study, participants (N = 207, 76% female) completed a German translation of the PCTS and other questionnaires online.

RESULTS

A one-factor structure had good model fit and the PCTS had acceptable internal reliability and good test-retest reliability across an average of four and a half weeks. Higher plate clearing tendencies related to more frequent parental encouragement to clear one's plate in childhood and to stronger food waste concerns but were unrelated to sex, body weight, self-control, and eating behaviors. However, higher plate clearing tendencies related to higher body weight in unsuccessful dieters.

CONCLUSION

The current study shows that the PCTS has sound psychometric properties and that plate clearing tendencies appear to be largely driven by food waste concerns and not by automatic eating habits or low eating-related self-control. In dieters, however, high plate clearing tendencies may contribute to low dieting success and hinder weight loss.

LEVEL OF EVIDENCE

No level of evidence, basic science.

Sociocultural Influences Contribute to Overeating and Unhealthy Eating: Creating and Maintaining an Obesogenic Social Environment in Indigenous Communities in Urban Fiji

Pacific Island countries (PICs), such as Fiji, lead the world statistics in obesity and deaths caused by non-communicable diseases. The impacts of obesity overburden the healthcare system and social services and have major impacts on the Fijian economy. This study is the first of its kind to undertake an in-depth exploration of the determinants of the obesity epidemic in PICs by exploring the sociocultural influences and situations that impact nutrient transitions, overconsumption, and unhealthy eating in an urban indigenous community. In-depth qualitative interviews were conducted with 15 indigenous Fijian women from the largest urban center in Fiji who self-identified as gatekeepers of family meal planning, preparing, and shopping for groceries, fruits, and vegetables. The women identified several cultural norms and expectations of both the individuals providing the food and the individuals consuming the food that create and maintain an obesogenic social environment. Moreover, participants also shared a misplaced value on meat, energy-dense foods, junk food, and fast foods that further contribute to unhealthy eating and overeating within this urban indigenous community. These novel findings highlight the importance of considering sociocultural influences on unhealthy eating and overeating and may be used to assist decision-makers in developing contextualized obesity prevention strategies and health messaging to target obesity in this community.

The relationship between traditional and common Japanese childhood education and adulthood towards avoiding food waste behaviors

Japanese parents and educators teach children to refrain from leaving food in their plates. Their teachings have direct (advising children to refrain from leaving food uneaten) and indirect (meal-related rituals before and after mealtimes) influence in enhancing gratitude for food in daily life. This cross-sectional study aimed to examine 1) the interaction of direct and indirect approaches to avoiding food waste behaviors and 2) the mediation of gratitude for food by preventing such behaviors. Overall, 400 Japanese adults (female: n = 200) responded to a self-administrated anonymous questionnaire survey measuring: the present food waste avoiding behaviors; current gratitude for food; direct and indirect childhood approaches for avoiding food waste behaviors. Participants' mean (standard deviation) age and body mass index were 40.0 (11.6) and 21.9 (3.9), respectively. A significant main effect of the indirect approach and the interaction of direct and indirect approaches were obtained by adjusting the participants' background. Moreover, through mediation analyses with percentile-corrected bootstrap confidence intervals, it was observed that gratitude for food mediated the association between direct and indirect childhood approaches and avoiding food waste behaviors. Despite no information on the current meal-related rituals of the respondents, this study suggests the potential of these approaches in enhancing gratitude for food as a new approach to reduce food waste worldwide.

"Waste not and stay at home" evidence of decreased food waste during the COVID-19 pandemic from the U.S. and Italy

The COVID-19 pandemic has profoundly disrupted household food purchasing and preparation, including elements identified as important drivers of household food waste. The two main aims of this study were (1) to examine changes in food waste behaviors since the start of the COVID-19 pandemic in the U.S. and Italy; and (2) to investigate potential predictors of food waste behavior, including avoidance of supermarkets, increased home cooking, and increased role of health concerns in food choices. A sample of n = 478 (79% female) individuals from the U.S., mean (SD) age = 30.51 (10.85), and n = 476 individuals from Italy, (78% female), mean (SD) age = 33.84 (12.86), completed an online survey between April 8th and April 28^th 2020. Just under half of respondents (49%) reported decreased food waste since the start of the pandemic. Rates were significantly higher among the U.S. sample (61.5%, n = 294) compared to the Italian sample (38%, n = 180). Controlling for the time since restrictions were introduced, age, gender, and perceived financial security, logistic regression revealed greater reduction in food waste since the beginning of the pandemic for U.S. individuals relative to participants from Italy (OR = 0.47, p < .001). In addition, increased importance of health concerns when making food choices (OR = 1.34, p < .005) as well as more frequent cooking (OR = 1.35, p < .001), and greater avoidance of supermarkets (OR = 1.15, p = .049) were associated with greater probability of less food waste. Scarcity and greater reliance on cooking may encourage individuals to reflect on food waste practices. Further research should explore how these factors may be targeted to reduce food waste beyond the pandemic.

Food waste concerns, eating behaviour and body weight

Consumer food waste is now a significant social issue. However, given that the modern day food environment has become characterised by larger portion sizes of more energy-dense foods, personal concerns about wasting food may result in eating behaviours that promote excess energy intake and weight gain. Across 3 studies, we developed a brief (5-item) measure to quantify concerns about food waste and examined the relationships between food waste concerns, eating behaviour and body weight. In Study 1, we showed that our 5-item measure of food waste concerns has acceptable convergent and divergent validity, and test-retest reliability. We also found that concerns about wasting food were predictive of greater behavioural intentions to avoid food waste (e.g. eating leftovers). In Study 2, greater food waste concerns were associated with an increased tendency to plate-clear when eating (self-reported), but not with objectively measured body weight or likelihood of having overweight or obesity. In Study 3, we examined how much food participants consumed when served a large portion size of a lunchtime meal and found that food waste concerns did not directly or indirectly predict how much participants ate. Overall, we found evidence that concerns about food waste are related to self-reported intentions to minimize food waste and plate-clearing tendencies, but no evidence that food waste concerns are related to objectively measured energy intake in the laboratory or body weight.

Portion size normality and additional within-meal food intake: two crossover laboratory experiments

Reducing food portion size could reduce energy intake. However, it is unclear at what point consumers respond to reductions by increasing intake of other foods. We predicted that a change in served portion size would only result in significant additional eating within the same meal if the resulting portion size was no longer visually perceived as 'normal'. Participants in two crossover experiments (Study 1: n 45; Study 2: n 37; adults, 51 % female) were served different-sized lunchtime portions on three occasions that were perceived by a previous sample of participants as 'large-normal', 'small-normal' and 'smaller than normal', respectively. Participants were able to serve themselves additional helpings of the same food (Study 1) or dessert items (Study 2). In Study 1 there was a small but significant increase in additional intake when participants were served the 'smaller than normal' compared with the 'small-normal' portion (m difference = 161 kJ, P = 0·002, d = 0·35), but there was no significant difference between the 'small-normal' and 'large-normal' conditions (m difference = 88 kJ, P = 0·08, d = 0·24). A similar pattern was observed in Study 2 (m difference = 149 kJ, P = 0·06, d = 0·18; m difference = 83 kJ, P = 0·26, d = 0·10). However, smaller portion sizes were each associated with a significant reduction in total meal intake. The findings provide preliminary evidence that reductions that result in portions appearing 'normal' in size may limit additional eating, but confirmatory research is needed.

Doggy bags and downsizing: Packaging uneaten food to go after a meal attenuates the portion size effect in women

Serving larger portions leads to increased food and energy intake, but little is known about strategies to moderate this response. This study tested how the effect of portion size on meal intake was influenced by providing the option to take away uneaten food in a "doggy bag" (to-go container). Women were randomly assigned to one of two subject groups: a To-Go Group (n = 27) that was informed before each meal that their leftover food would be packaged to take away after the meal, and a Control Group (n = 26) that was not given this option. In a crossover design, subjects came to the lab once a week for four weeks to eat a dinner composed of five foods. Across meals, the portion size of all foods was varied (100%, 125%, 150%, and 175% of baseline). Results showed that the portion size effect, defined as the trajectory of intake across the weight of food served, differed significantly by subject group (P ≤ 0.025). In the Control Group, increasing the portion size of all foods led to substantial increases in intake (P < 0.0001); for every 100 g added to the baseline portion, women in this group consumed an additional mean (±SEM) of 64 ± 12 g of food and 90 ± 19 kcal, until intake leveled off. In contrast, intake of women in the To-Go Group increased by only 17 ± 12 g and 19 ± 18 kcal for every additional 100 g served; these increases did not differ significantly from zero (P > 0.15). Thus, the effect of portion size on intake was attenuated in the To-Go Group compared to the Control Group. These data indicate that packaging uneaten food after a meal could be an effective strategy to reduce overconsumption from large portions.

Plate-clearing tendencies and portion size are independently associated with main meal food intake in women: A laboratory study

BACKGROUND

Larger portion sizes of food promote increased food intake, although the mechanisms explaining the portion size effect are unclear. In the present study we examined whether the tendency to clear one's plate when eating is associated with greater food intake in response to larger portion size.

METHOD

We recruited female participants who were either self-reported habitual plate clearers (N = 48) or non-plate clearers (N = 41) into a laboratory study. In a between-subjects design, participants were served either a 'normal' (500 g) or 'large' (1000 g) portion of pasta for lunch and ate as much as they desired.

RESULTS

There was no significant interaction found between portion size and plate-clearing tendencies; portion size had a similar sized effect on food intake in both plate clearers and non-plate clearers. A significant main effect of portion size was found, whereby participants consumed significantly more when served the large versus the normal portion (100.55 g difference, p < .001, η_p²  = 0.16). There was also a significant main effect of plate clearing; participants with a tendency to clear their plate when eating consumed significantly more than non-plate clearers (68.21 g difference, p = .006, η_p²  = 0.08).

CONCLUSIONS

The tendency to clear one's plate when eating was associated with increased food intake during a lunchtime meal. Increasing the portion size of the lunchtime meal increased food intake, although the tendency for a larger portion size to increase food intake was observed irrespective of participant plate-clearing tendencies.