Impact of Portion Control Tools on Portion Size Awareness, Choice and Intake: Systematic Review and Meta-Analysis.

Portion control utensils and reduced size tableware amongst other tools, have the potential to guide portion size intake but their effectiveness remains controversial. This review evaluated the breadth and effectiveness of existing portion control tools on learning/awareness of appropriate portion sizes (PS), PS choice, and PS consumption. Additional outcomes were energy intake and weight loss. Published records between 2006-2020 (n = 1241) were identified from PubMed and WoS, and 36 publications comparing the impact of portion control tools on awareness (n = 7 studies), selection/choice (n = 14), intake plus related measures (n = 21) and weight status (n = 9) were analyzed. Non-tableware tools included cooking utensils, educational aids and computerized applications. Tableware included mostly reduced-size and portion control/calibrated crockery/cutlery. Overall, 55% of studies reported a significant impact of using a tool (typically smaller bowl, fork or glass; or calibrated plate). A meta-analysis of 28 articles confirmed an overall effect of tool on food intake (d = -0.22; 95%CI: -0.38, -0.06; 21 comparisons), mostly driven by combinations of reduced-size bowls and spoons decreasing serving sizes (d = -0.48; 95%CI: -0.72, -0.24; 8 comparisons) and consumed amounts/energy (d = -0.22; 95%CI: -0.39, -0.05, 9 comparisons), but not by reduced-size plates (d = -0.03; 95%CI: -0.12, 0.06, 7 comparisons). Portion control tools marginally induced weight loss (d = -0.20; 95%CI: -0.37, -0.03; 9 comparisons), especially driven by calibrated tableware. No impact was detected on PS awareness; however, few studies quantified this outcome. Specific portion control tools may be helpful as potentially effective instruments for inclusion as part of weight loss interventions. Reduced size plates per se may not be as effective as previously suggested.

Can Visual Cues to Portion Size Reduce the Number of Portions of Consumed? Two Randomized Controlled Trials.

BACKGROUND: Since 1950, the portion size of many snack foods has more than doubled and obesity rates have tripled. Portion size determines energy intake, often unwittingly. PURPOSE: This paper tests whether salient visual cues to portion size on the packaging of high fat, sugar, or salty (HFSS) snacks can reduce consumption. METHODS: Two preregistered randomized controlled trials (N = 253 and N = 674) measured consumption in a lab and the home environment. Cues were salient, labeled stripes that demarcated single portions. Participants were randomized to cue condition or control. Consumption was measured without awareness. RESULTS: The main preregistered effect of the visual cue was not statistically significant. There was some variation by subgroup. In Study 1, men were more likely to eat the whole can of potato chips than women but significantly reduced consumption when visual cues were on the pack. The effect size was large: the number of men eating more than the recommended portion fell by 33%. Study 2 monitored household consumption of chocolate biscuits (cookies) sent to family homes in gift packs. Again, the main effect was nonsignificant but there was significant subgroup variation. When the person receiving the biscuits was female, households were more likely to eat more than the recommended portion per person per day, but less likely when the visual cues were displayed. The gender of the eaters was not known. The effect size was again large: the number of households eating more than the recommended portion fell by 26%. Households with children were also less likely to open packs with visual cues compared to control packs. Both studies recorded significant increases in the likelihood of observing serving size information, together with confusion about what it means. CONCLUSIONS: The studies offer some evidence that salient visual cues could play a role in tackling the high consumption of unhealthy snacks, but the effects are confined to specific subgroups and warrant further investigation.

Does Unit-Dose Packaging Influence Understanding of Serving Size Information for Cannabis Edibles?

OBJECTIVE: Edible cannabis products have increased in popularity, particularly in jurisdictions that have legalized nonmedical cannabis. Rates of adverse events from cannabis edibles have also increased, in part because of difficulties identifying and titrating tetrahydrocannabinol (THC) levels. The current study tested whether packaging cannabis in separate units enhances consumer understanding of serving sizes. METHOD: An experimental task was conducted as part of the 2018 International Cannabis Policy Study online survey. Participants were recruited from the Nielsen Global Insights Consumer Panel. A total of 26,894 participants (61.5% female) ages 16-65 years from Canada and the United States were randomly assigned to view a cannabis brownie packaged according to one of three conditions: (a) multiserving edible ("control condition"), (b) single-serving edible, and (c) single-serving edible packaged separately ("unit-dose packaging"). Participants were asked to identify a standard serving based on information on the product label. Logistic regression was used to test the influence of packaging condition on the likelihood of a correct response, adjusting for key covariates. RESULTS: Compared with the multiserving edible control (50.6%), participants were significantly more likely to correctly identify the serving size in the single-serving edible condition (55.3%; adjusted odds ratio = 1.22, CI [1.15, 1.29], p < .001) and the unit-dose packaging condition (54.3%; adjusted odds ratio = 1.17, CI [1.10, 1.24], p < .001). CONCLUSIONS: Packaging in which each product unit contained one dose of THC enhanced consumers' ability to identify how much of a product constitutes a standard serving or dose. Packaging products as individual doses eliminates the need for mental math and could reduce the risk of accidental overconsumption of cannabis.

Cannabis labelling and consumer understanding of THC levels and serving sizes.

OBJECTIVE: As part of cannabis legalization in Canada and several US states, regulations specify how THC levels should be labelled on products; however, there is little evidence on the extent to which consumers understand and use THC labelling to inform consumption amounts. The current study was designed to assess comprehension of cannabis-related information including communication of dose and strength of product on different labelling designs among young Canadians. METHODS: Two experiments were conducted in October 2017 among Canadian youth and young adults aged 16-30 years as part of an online cross-sectional survey (N = 870). Experiment 1 randomized respondents to one of three labelling conditions (1=No Label, 2=mgTHC, 3=Doses). Respondents interpreted a recommended serving and number of servings contained in the package. Experiment 2 randomized respondents to one of four labelling conditions communicating THC level (1=No Label, 2=%THC, 3=mgTHC, 4=Traffic Light System). Respondents determined level of THC in the product. RESULTS: Labelling the number of doses per package was associated with the greatest proportion of correct responses (54.1 %) when respondents had to determine a recommended serving compared with the no-label control condition (7.4 %) and THC mg condition (13.4 %). When cannabis products were labelled using a traffic light system, participants were more likely to identify THC level: low THC (85.1 %) or high THC (86.4 %) than the control condition (2.0 % and 5.2 % respectively). CONCLUSION: Few consumers can understand and apply quantitative THC labelling; in contrast, THC labels that provide 'interpretive' information, such as descriptors, symbols, or references to servings have greater efficacy.

Between- and Within-Subjects Predictors of the Kilocalorie Content of Bites of Food.

BACKGROUND: This study builds on previous research that seeks to estimate kilocalorie intake through microstructural analysis of eating behaviors. As opposed to previous methods, which used a static, individual-based measure of kilocalories per bite, the new method incorporates time- and food-varying predictors. A measure of kilocalories per bite (KPB) was estimated using between- and within-subjects variables. OBJECTIVE: The purpose of this study was to examine the relationship between within-subjects and between-subjects predictors and KPB, and to develop a model of KPB that improves over previous models of KPB. Within-subjects predictors included time since last bite, food item enjoyment, premeal satiety, and time in meal. Between-subjects predictors included body mass index, mouth volume, and sex. PARTICIPANTS/SETTING: Seventy-two participants (39 female) consumed two random meals out of five possible meal options with known weights and energy densities. There were 4,051 usable bites measured. MAIN OUTCOME MEASURES: The outcome measure of the first analysis was KPB. The outcome measure of the second analysis was meal-level kilocalorie intake, with true intake compared to three estimation methods. STATISTICAL ANALYSES PERFORMED: Multilevel modeling was used to analyze the influence of the seven predictors of KPB. The accuracy of the model was compared to previous methods of estimating KPB using a repeated-measured analysis of variance. RESULTS: All hypothesized relationships were significant, with slopes in the expected direction, except for body mass index and time in meal. In addition, the new model (with nonsignificant predictors removed) improved over earlier models of KPB. CONCLUSIONS: This model offers a new direction for methods of inexpensive, accurate, and objective estimates of kilocalorie intake from bite-based measures.

Size Matters: Package Size Influences Recognition of Serving Size Information.

PURPOSE: To identify the impact of package size on an individual's use of serving size information. The hypothesis was that participants would make more serving size assumption errors on a nutrition facts table (NFT) interpretation task when assessing packages that appear as a single serving but contain multiple servings, compared with products that appear as a multi-serving and contain multiple servings. METHODS: Sixty participants were randomized into 1 of 3 conditions (n = 20 each); products that appeared as a single serving and contain a single serving (SSSS), products that appeared as a single serving and contain multiple servings (SSMS), and products that both appear as a multi-serving and contain multiple servings (MSMS). All 3 conditions were tested on a NFT interpretation task while participants were being presented food items that were appropriate to their given condition. RESULTS: Participants in the SSMS (9.55 ± 7.78) condition made significantly more serving size assumption errors than the SSSS (0.00 ± 0.00; P < 0.001) and MSMS (0.40 ± 0.75; P < 0.001) conditions. CONCLUSIONS: Participants did not address serving size information when they perceived a product to be a single serving. This resulted in people misinterpreting nutritional and caloric content of foods that were single unit foods with multiple servings.

Food deprivation reduces the susceptibility to size-contrast illusions.

Hunger, caused by mild amount of food deprivation, is an everyday physiological state familiar to us all. Ongoing research has pinpointed the way hunger affects people's physiological functions as well as their attitudes and allocation of attention toward domain-specific, food-related objects. Yet, little is known about the way food deprivation affects basic perceptual abilities. Here, we utilized size-contrast visual illusions commonly associated with food to explore the way deprivation affects relative processing of food size. In two experiments (Nexp1 = 32 females, mean age: 24.31; Nexpt2 = 41 females, 40 males, mean age: 23.84), we examined the effect food deprivation has on participants' susceptibility to the Delboeuf illusion, which biases the perceived size of a neutral or of a food-related object when it is placed within the context of another object (e.g., a pizza is perceived as smaller when placed on a larger plate or tray). The results showed that food deprivation reduces the illusory bias for food-related but not for neutral stimuli. Such reduction in the illusory effect indicates reliance on analytic, rather than on relative processing style, for domain-specific stimuli when in the state of hunger.

The effect of the labelled serving size on consumption: A systematic review.

Guidance for food consumption and portion control plays an important role in the global management of overweight and obesity. Carefully conceptualised serving size labelling can contribute to this guidance. However, little is known about the relationship between the information that is provided regarding serving sizes on food packages and levels of actual food consumption. The aim of this systematic review was to investigate how serving size information on food packages influences food consumption. We conducted a systematic review of the evidence published between 1980 and March 2018. Two reviewers screened titles and abstracts for relevance and assessed relevant articles for eligibility in full-text. Five studies were considered eligible for the systematic review. In three of the included studies, changes in serving size labelling resulted in positive health implications for consumers, whereby less discretionary foods were consumed, if serving sizes were smaller or if serving size information was provided alongside contextual information referring to the entire package. One study did not find significant differences between the conditions they tested and one study suggested a potentially negative impact, if the serving size was reduced. The influence of labelled serving size on consumption of non-discretionary foods remains unclear, which is partially due to the absence of studies specifically focusing on non-discretionary food groups. Studies that investigate the impact of serving size labels within the home environment and across a broad demographic cross-section are required.

An overture to overeating: The cross-modal effects of acoustic pitch on food preferences and serving behavior.

Billions of dollars are spent annually with the aim of enticing consumers to purchase food. Yet despite the prevalence of such advertising, little is known about how the actual sensation of this advertising media affects consumer behavior, including consequential choices regarding food. This paper explores the effect of acoustic pitch in food advertising, demonstrating in two studies, including a field study in a live retail environment, how the perception of pitch in advertising can impact food desirability and decisions regarding serving size. In study 1, a field study, pitch affects actual serving sizes and purchase behavior in a live, self-serve retail setting, with low pitch leading to larger serving sizes. Study 2 demonstrates how low pitch increases desire for a food product among hungry consumers, and that this effect is mediated by perceptions of size and how filling consumers believe the product will be. We discuss these results in the context of cross-modal correspondence and mental imagery.

Age differences in the use of serving size information on food labels: numeracy or attention?

OBJECTIVE: The ability to use serving size information on food labels is important for managing age-related chronic conditions such as diabetes, obesity and cancer. Past research suggests that older adults are at risk for failing to accurately use this portion of the food label due to numeracy skills. However, the extent to which older adults pay attention to serving size information on packages is unclear. We compared the effects of numeracy and attention on age differences in accurate use of serving size information while individuals evaluated product healthfulness. DESIGN: Accuracy and attention were assessed across two tasks in which participants compared nutrition labels of two products to determine which was more healthful if they were to consume the entire package. Participants' eye movements were monitored as a measure of attention while they compared two products presented side-by-side on a computer screen. Numeracy as well as food label habits and nutrition knowledge were assessed using questionnaires. SETTING: Sacramento area, California, USA, 2013-2014. SUBJECTS: Stratified sample of 358 adults, aged 20-78 years. RESULTS: Accuracy declined with age among those older adults who paid less attention to serving size information. Although numeracy, nutrition knowledge and self-reported food label use supported accuracy, these factors did not influence age differences in accuracy. CONCLUSIONS: The data suggest that older adults are less accurate than younger adults in their use of serving size information. Age differences appear to be more related to lack of attention to serving size information than to numeracy skills.

To squeeze or not to squeeze: How squeeze tubes affect consumers' serving sizes.

Squeeze tubes increasingly complement traditional packaging. But, would squeeze tubes - besides offering ease of use - also affect consumers' serving sizes? And if so, in what way? To answer these questions, we contrast the motor fluency hypothesis (i.e., bodily movements affect judgments) with the consumption monitoring hypothesis (i.e., paying attention to quantities eaten affects consumption). Two studies reveal that consumers use less of a product when it comes in a squeeze tube versus a traditional container, providing initial evidence for the consumption monitoring hypothesis. A third study also provides evidence that the ease of consumption monitoring drives the squeeze tube effect, which is more prominent for unrestrained eaters. These findings have important implications for consumers, public policy makers, and product manufacturers.

Usage and Understanding of Serving Size Information on Food Labels in the United States.

PURPOSE: To investigate consumer understanding and usage of serving size (SS) information on Nutrition Facts (NF) labels. DESIGN: We analyzed three data sources: (1) U.S. Food and Drug Administration (FDA) Health and Diet Survey (HDS) 1994 (n = 1945), 1995 (n = 1001), and 2008 (n = 2584); (2) National Health and Nutrition Examination Survey (NHANES) 2005-2006 and 2007-2008 (n = 10,750); and (3) 2011 FDA Nutrition Facts Label Experimental Study (NFLES) (n = 9493). Data from FDA are cross-sectional and we focused on usage and meaning of SS. SETTING: United States. SUBJECTS: Adults (18+ years). MEASURES: Both HDS and NHANES addressed how often participants used SS information and HDS also asked how SS is determined. Both NHANES and NFLES contained similar questions on the meaning of SS but NFLES also included an open-ended response option. ANALYSIS: We included both quantitative and qualitative measures. Questions were analyzed by demographic variables and body mass index with frequencies, cross-tabulations, and χ(2) statistics reported. RESULTS: HDS showed that the percentage of consumers who used SS information often or sometimes increased from 54% in 1994 to 64% in 2008. NHANES and NFLES data indicated that a majority of respondents had misinterpreted the meaning of SS. Women and obese individuals were more likely to use SS often or sometimes, but were also more likely to misinterpret the meaning of SS. A small subsample of NFLES participants expressed a distrust of the SS information. CONCLUSION: There is a widespread misunderstanding about SS, suggesting the need for clearer NF labels or enhanced education efforts.

Small, medium, large or supersize? The development and evaluation of interventions targeted at portion size.

In the past decades, portion sizes of high-caloric foods and drinks have increased and can be considered an important environmental obesogenic factor. This paper describes a research project in which the feasibility and effectiveness of environmental interventions targeted at portion size was evaluated. The studies that we conducted revealed that portion size labeling, offering a larger variety of portion sizes, and proportional pricing (that is, a comparable price per unit regardless of the size) were considered feasible to implement according to both consumers and point-of-purchase representatives. Studies into the effectiveness of these interventions demonstrated that the impact of portion size labeling on the (intended) consumption of soft drinks was, at most, modest. Furthermore, the introduction of smaller portion sizes of hot meals in worksite cafeterias in addition to the existing size stimulated a moderate number of consumers to replace their large meals by a small meal. Elaborating on these findings, we advocate further research into communication and marketing strategies related to portion size interventions; the development of environmental portion size interventions as well as educational interventions that improve people's ability to deal with a 'super-sized' environment; the implementation of regulation with respect to portion size labeling, and the use of nudges to stimulate consumers to select healthier portion sizes.

Opportunities and barriers for smaller portions in food service: lessons from marketing and behavioral economics.

This paper uses the frameworks and evidence from marketing and behavioral economics to highlight the opportunities and barriers for portion control in food service environments. Applying Kahneman's 'thinking fast and slow' concepts, it describes 10 strategies that can be effective in 'tricking' the consumer's fast cognitive system to make better decisions and in triggering the slow cognitive system to help prevent the fast system from making bad decisions. These strategies include shrinking defaults, elongating packages, increasing the visibility of small portions, offering more mixed virtue options, adding more small sizes, offering 'right-sized' standard portions, using meaningful size labels, adopting linear pricing, using temporal landmarks to push smaller portions and facilitating pre-commitment. For each of these strategies, I discuss the specific cost and revenue barriers that a food service operator would face if the strategy were adopted.

Estimating food portions. Influence of unit number, meal type and energy density.

Estimating how much is appropriate to consume can be difficult, especially for foods presented in multiple units, those with ambiguous energy content and for snacks. This study tested the hypothesis that the number of units (single vs. multi-unit), meal type and food energy density disrupts accurate estimates of portion size. Thirty-two healthy weight men and women attended the laboratory on 3 separate occasions to assess the number of portions contained in 33 foods or beverages of varying energy density (1.7-26.8 kJ/g). Items included 12 multi-unit and 21 single unit foods; 13 were labelled "meal", 4 "drink" and 16 "snack". Departures in portion estimates from reference amounts were analysed with negative binomial regression. Overall participants tended to underestimate the number of portions displayed. Males showed greater errors in estimation than females (p=0.01). Single unit foods and those labelled as 'meal' or 'beverage' were estimated with greater error than multi-unit and 'snack' foods (p=0.02 and p<0.001 respectively). The number of portions of high energy density foods was overestimated while the number of portions of beverages and medium energy density foods were underestimated by 30-46%. In conclusion, participants tended to underestimate the reference portion size for a range of food and beverages, especially single unit foods and foods of low energy density and, unexpectedly, overestimated the reference portion of high energy density items. There is a need for better consumer education of appropriate portion sizes to aid adherence to a healthy diet.