What to do about portion sizes? Roundtable discussion at the Forefronts in Portion Size Conference

Differences in Portion Sizes in Brazil, France, and the USA

Portion size is recognized as a major determinant of food intake, at least over the short term, and could be related to overconsumption and obesity. In this study, we developed and evaluated a new visual measure of portion size (PS), examined whether the PS of chicken, ice cream, and soda varied among people in Brazil, France, and the USA, and tested whether PS was related to gender, body mass index, body weight, and socioeconomic status. We conducted a cross-sectional study using online convenience samples of university students (total N = 1391). Across all three foods, French personal and country PSs were significantly smaller than the other three countries. Estimated country PS was reliably larger than personal PS. Women's personal PSs were smaller than men's, but women's and men's estimates for country PS were similar. French personal and country PSs were the lowest. Some PSs had a weak but significant correlation with SES but were not significantly related to either weight or BMI. The study confirms French-American differences in personal PS and demonstrates that perceived norms correspond to individual PS.

Measured energy content of frequently purchased restaurant meals: multi-country cross sectional study

OBJECTIVE

To measure the energy content of frequently ordered meals from full service and fast food restaurants in five countries and compare values with US data.

DESIGN

Cross sectional survey.

SETTING

223 meals from 111 randomly selected full service and fast food restaurants serving popular cuisines in Brazil, China, Finland, Ghana, and India were the primary sampling unit; 10 meals from five worksite canteens were also studied in Finland. The observational unit was frequently ordered meals in selected restaurants.

MAIN OUTCOME MEASURE

Meal energy content, measured by bomb calorimetry.

RESULTS

Compared with the US, weighted mean energy of restaurant meals was lower only in China (719 (95% confidence interval 646 to 799) kcal versus 1088 (1002 to 1181) kcal; P<0.001). In analysis of variance models, fast food contained 33% less energy than full service meals (P<0.001). In Finland, worksite canteens provided 25% less energy than full service and fast food restaurants (mean 880 (SD 156) versus 1166 (298); P=0.009). Country, restaurant type, number of meal components, and meal weight predicted meal energy in a factorial analysis of variance (R²=0.62, P<0.001). Ninety four per cent of full service meals and 72% of fast food meals contained at least 600 kcal. Modeling indicated that, except in China, consuming current servings of a full service and a fast food meal daily would supply between 70% and 120% of the daily energy requirements for a sedentary woman, without additional meals, drinks, snacks, appetizers, or desserts.

CONCLUSION

Very high dietary energy content of both full service and fast food restaurant meals is a widespread phenomenon that is probably supporting global obesity and provides a valid intervention target.

Big hearts, small hands: a focus group study exploring parental food portion behaviours

BACKGROUND

The development of healthy food portion sizes among families is deemed critical to childhood weight management; yet little is known about the interacting factors influencing parents' portion control behaviours. This study aimed to use two synergistic theoretical models of behaviour: the COM-B model (Capability, Opportunity, Motivation - Behaviour) and Theoretical Domains Framework (TDF) to identify a broad spectrum of theoretically derived influences on parents' portion control behaviours including examination of affective and habitual influences often excluded from prevailing theories of behaviour change.

METHODS

Six focus groups exploring family weight management comprised of one with caseworkers (n = 4), four with parents of overweight children (n = 14) and one with parents of healthy weight children (n = 8). A thematic analysis was performed across the dataset where the TDF/COM-B were used as coding frameworks.

RESULTS

To achieve the target behaviour, the behavioural analysis revealed the need for eliciting change in all three COM-B domains and nine associated TDF domains. Findings suggest parents' internal processes such as their emotional responses, habits and beliefs, along with social influences from partners and grandparents, and environmental influences relating to items such as household objects, interact to influence portion size behaviours within the home environment.

CONCLUSION

This is the first study underpinned by COM-B/TDF frameworks applied to childhood weight management and provides new targets for intervention development and the opportunity for future research to explore the mediating and moderating effects of these variables on one another.

Combining food type(s) and food quantity choice in a new food choice paradigm based on vice-virtue bundles

Given the prevalence and rising rates of obesity in many countries, including the United States, much food decision-making research ultimately aims at understanding how consumers can make healthier choices. The two predominant choice paradigms used in food decision-making research ask consumers to choose (a) between a "vice" (or unhealthy food) and a "virtue" (or healthy food) or (b) among varying portion sizes of "vice." We propose a new food choice paradigm that encourages consumers to jointly consider both food type(s) choice and food portion size at each decision point. The purpose of this paradigm is two-fold. First, it aims to allow examination of more comprehensive eating behavior (e.g., to examine the overall composition of a plate of food rather than choice of a single food). Second, it aims to shift consumers towards including large proportions of virtues and smaller proportions of vice in their overall consumption portfolios. For this paradigm, we draw upon a recently introduced food product innovation called "vice-virtue bundles" (Liu et al., 2015) that illustrates the basis of this new food choice paradigm, in which food type(s) and portion decisions are made simultaneously. Accordingly, we first discuss relevant findings on vice-virtue bundles as well as the differences between simultaneous and sequential choice of multiple products. Second, we examine the benefits for managing and controlling one's consumption that are provided by vice-virtue bundles and this joint food choice paradigm more generally. Third and finally, we point out opportunities for future research by discussing (a) multiple factors that influence food choices, (b) decision processes affected by food choice paradigms, and (c) issues of generalizability related to the presence of vice-virtue bundles.

The Influence of Portion Size and Timing of Meals on Weight Balance and Obesity

This review focuses on the influence of portion size and temporal distribution of food intake on weight balance and obesity in adults. The inconsistency of definitions in the area of meal patterns is also discussed. The conclusion is that regular eating habits might facilitate weight balance, while unplanned snacking as well as consuming the major part of the energy intake at the end of the day seem to be unfavourable. Altogether, the research suggests that large portions promote over-consumption and, therefore, limiting portion size of energy dense foods and drinks with added sugar could be recommended. Even if more research is needed, these factors should be taken into consideration in recommendations for obesity prevention.