Reducing Portion Sizes Research Articles

A review of evidence supporting current strategies, challenges, and opportunities to reduce portion sizes

Although there is considerable evidence for the portion-size effect and its potential impact on health, much of this has not been successfully applied to help consumers reduce portion sizes. The objective of this review is to provide an update on the strength of evidence supporting strategies with potential to reduce portion sizes across individuals and eating contexts. Three levels of action are considered: food-level strategies (targeting commercial snack and meal portion sizes, packaging, food labels, tableware, and food sensory properties), individual-level strategies (targeting eating rate and bite size, portion norms, plate-cleaning tendencies, and cognitive processes), and population approaches (targeting the physical, social, and economic environment and health policy). Food- and individual-level strategies are associated with small to moderate effects; however, in isolation, none seem to have sufficient impact on food intake to reverse the portion-size effect and its consequences. Wider changes to the portion-size environment will be necessary to support individual- and food-level strategies leading to portion control.

Working on healthy choices

Working on healthy choices

Identifying Barriers to Reducing Portion Size: A Qualitative Focus Group Study of British Men and Women.

Reducing portion size might reduce meal satisfaction, which could minimize adherence to portion size interventions. The present study sought to identify the perceived barriers for consumers to eat smaller portions. A secondary aim explored the relative contribution of enjoyment of taste and post-meal fullness as determinants of meal satisfaction. Focus groups (N = 42) evaluated consumers’ feelings toward a small reduction in portion size. Thematic analysis of written free association tasks and open-ended group discussions revealed that most participants expected to feel hungry and unsatisfied, which motivated them to consume something else. However, others expected to feel comfortable, healthy, and virtuous. The acceptability of the reduced portion was also determined by meal characteristics (e.g., time and setting) and individual characteristics (e.g., predicted energy requirements). Compared to post-meal fullness, enjoyment of taste was perceived to be the more important determinant of meal satisfaction. In conclusion, interventions should present portion reduction as a marginal modification with little physiological consequence to energy reserves, while emphasizing the positive feelings (e.g., comfort, satisfaction, and self-worth) experienced after consuming a smaller portion. Additionally, focusing on taste enjoyment (rather than fullness) might be a useful strategy to maintain meal satisfaction despite a reduction in meal size.

Viewpoint: Effectiveness or consumer acceptance? Tradeoffs in selecting healthy eating nudges

Governments and companies that want to promote healthier eating must consider both the effectiveness and the acceptance of the ‘nudges’ given to consumers. Our review of the literature uncovers a wide range of nudges towards healthy eating, from nutrition labeling to portion size reductions, which are found to vary greatly in effectiveness and levels of public acceptance (64% of women; 52% of men). Acceptance of a nudge is inversely related to its effectiveness: only 43% of respondents approved the most effective intervention – portion and package size reductions. Approval levels increased with the perceived effectiveness of the nudge and with the perception that the nudge is good for both health and business (as opposed to only one of the two), especially among respondents who identify as conservatives. To encourage acceptance of the most effective nudge strategies, governments and companies should therefore correct misconceptions about which nudges work best, and should underscore the win-win potential for health and business.

What makes people leave LESS food? Testing effects of smaller portions and information in a behavioral model

To contribute to a better understanding of consumer food leftovers and to facilitate their reduction in out-of-home settings, our study analyzes the effects of two common intervention strategies for reducing leftovers in a holistic behavioral model. Based on a quasi-experimental baseline-intervention design, we analyzed how the display of information posters and the reduction of portion sizes take an effect on personal, social and environmental determinants in a structural equation model. Applying data from online surveys and observations among 880 guests (503 baseline, 377 intervention) during two weeks in a university canteen, the suggested model allows to assign effects from the two interventions on plate leftovers to specific changes in behavioral determinants. Portion size reductions for target dishes are found to relate to lower levels of plate waste based on conscious perception, represented in smaller portion size ratings. Effects from seeing information posters are found to base on changed personal attitudes, subjective norms and perceived behavioral control. However, depending on how an individual reacts to the information (by only making an effort to finish all food or by making an effort and additionally choosing a different dish in the canteen) there are opposite effects on these determinants and consequently also on plate leftovers. Overall, the differentiated results on intervention effects strongly support the benefits of more holistic and in-depth analyses of interventions to reduce plate leftovers and therefore to contribute to more sustainable food consumption in out-of-home settings.

Feasibility of working with a wholesale supplier to co-design and test acceptability of an intervention to promote smaller portions: an uncontrolled before-and-after study in British Fish & Chip shops

ObjectivesTo explore the feasibility of working with a wholesale supplier to co-design and deliver, and to assess the acceptability of, an intervention to promote smaller portions in Fish & Chip...

Food portion size influences accompanying beverage selection in adults

When trying to reduce food portion size, it is important that meal satisfaction is, as far as possible, preserved. Otherwise, individuals may select accompaniments to the meal (e.g., snacks, beverages) to achieve satisfaction and, in doing so, negate any benefit of the original portion size reduction. This study investigated whether varying portion sizes of food would influence choice of accompanying beverages. That is, when presented with a food portion size that is smaller or larger than their ideal, an individual may compensate by choosing a beverage based on its satiating and/or orosensory properties to balance the expected satiation and satisfaction of a meal. Data from an online interactive study (n = 93) was analysed using multilevel ordinal logistic regression models. Food portion size (100, 300, 500, 700, or 900 kcal) predicted beverage choice (water, low-energy sweetened beverage, high-energy sweetened beverage). For example, the sweetened beverages were more likely to be selected with small food portion sizes (p < .001). Participant ideal food portion size did not interact with this relationship. Participants appear to have recognised that sweetened beverages provide flavour and/or energy, and used them to compensate for a smaller meal. While switching to a low-energy beverage with an increased food portion size is advantageous for energy balance, choosing a high-energy beverage with a decreased food portion size is likely to be detrimental for those attempting to reduce energy intake and body weight.

The effectiveness of a social media intervention for reducing portion sizes in young adults and adolescents.

ObjectiveAdolescents and young adults select larger portions of energy-dense food than recommended. The majority of young people have a social media profile, and peer influence on social media may moderate the size of portions selected.MethodsTwo pilot interventions examined whether exposure to images of peers’ portions of high-energy-dense (HED) snacks and sugar-sweetened beverages (SSBs) on social media (Instagram) would influence reported desired portions selected on a survey. Confederate peers posted ‘their’ portions of HED snacks and SSBs on Instagram. At baseline and intervention end participants completed surveys that assessed desired portion sizes.ResultsIn intervention 1, undergraduate students (n = 20, mean age=19.0 years, SD=0.65) participated in a two-week intervention in a within-subjects design. Participants reported smaller desired portions of HED snacks and SSBs following the intervention, and smaller desired portions of HED snacks for their peers. In intervention 2, adolescents (n = 44, mean age = 14.4 years, SD = 1.06) participated in a four-week intervention (n = 23) or control condition (n = 21) in a between-subjects design. Intervention 2 did not influence adolescents to reduce their reported desired portion sizes of HED snacks or SSBs relative to control.ConclusionsThese preliminary studies demonstrated that social media is a feasible way to communicate with young people. However, while the intervention influenced young adults’ reported desired portions and social norms regarding their peers’ portions, no significant impact on desired reported portion sizes was found for HED snacks and SSBs in adolescents. Desired portion sizes of some foods and beverages may be resistant to change via a social media intervention in this age group.

Larger Food Portion Sizes Are Associated with Both Positive and Negative Markers of Dietary Quality in Irish Adults.

Reduction in portion size, particularly for energy-dense foods, is increasingly addressed in healthy eating guidelines in a bid to tackle the obesity epidemic. The effect of portion size on other aspects of dietary quality, such as nutrient intakes, is less studied. The aim of the current work was to investigate associations between food portion sizes and key indicators of dietary quality, namely energy-adjusted intakes of saturated fat, dietary fibre, sodium, calcium, iron, folate and vitamin D, and dietary energy density (DED), in Irish adults on the days the foods were consumed. Data from the Irish National Adult Nutrition Survey (2008–2010) (n = 1274, 18–64 years, 4-day semi-weighed record) were used for the analysis. DED was lower on the days larger portions of boiled potatoes, fruit, vegetables and baked beans were consumed, and higher on the days larger portions of white bread, ready-to-eat breakfast cereals (RTEBCs), frying meats, cheese, butter, biscuits, chocolate and sugar-sweetened beverages were consumed. Micronutrient intakes were higher on the days larger portions of brown bread, RTEBCs, vegetables and low-fat spreads were consumed, and lower on the days larger portions of white bread, butter, biscuits, chocolate, sugar-sweetened beverages and beer/cider were consumed, with the exception of folate. The study identifies foods for which larger portion sizes may be associated with positive dietary attributes, as well as the opposite. It provides an important evidence base from which more specific dietary guidance on food portion sizes might be developed for Irish adults.

Using neuroimaging to investigate the impact of Mandolean\xae training in young people with obesity: a pilot randomised controlled trial

BackgroundSlowing eating rate using the Mandolean® previously helped obese adolescents to self-select smaller portion sizes, with no reduction in satiety, and enhanced ghrelin suppression. The objective of this pilot, randomised trial was to investigate the neural response to food cues following Mandolean® training using functional Magnetic Resonance Imaging (fMRI), and measures of ghrelin, PYY, glucose and self-reported appetite.MethodTwenty-four obese adolescents (11–18 years; BMI ≥ 95th centile) were randomised (but stratified by age and gender) to receive six-months of standard care in an obesity clinic, or standard care plus short-term Mandolean® training. Two fMRI sessions were conducted: at baseline and post-intervention. These sessions were structured as an oral glucose tolerance test, with food cue-reactivity fMRI, cannulation for blood samples, and appetite ratings taken at baseline, 30 (no fMRI), 60 and 90 min post-glucose. As this was a pilot trial, a conservative approach to the statistical analysis of the behavioural data used Cliff’s delta as a non-parametric measure of effect size between groups. fMRI data was analysed using non-parametric permutation analysis (RANDOMISE, FSL).ResultsFollowing Mandolean® training: (i) relatively less activation was seen in brain regions associated with food cue reactivity after glucose consumption compared to standard care group; (ii) 22% reduction in self-selected portion size was found with no reduction in post-meal satiety. However, usage of the Mandolean® by the young people involved was variable and considerably less than planned at the outset (on average, 28 meals with the Mandolean® over six-months).ConclusionThis pilot trial provides preliminary evidence that Mandolean® training may be associated with changes in how food cues in the environment are processed, supporting previous studies showing a reduction in portion size with no reduction in satiety. In this regard, the study supports targeting eating behaviour in weight-management interventions in young people. However, given the variable usage of the Mandolean® during the trial, further work is required to design more engaging interventions reducing eating speed.Trial registrationISRCTN, ISRCTN84202126, retrospectively registered 22/02/2018.

Cultivating self‐regulatory eating behaviours during childhood: The evidence and opportunities

AbstractGlobal high levels of obesity and metabolic disease have called for a reformulation of the food environment to reduce portion sizes and food energy density, particularly from added sugars, highlighting the importance of the food environment in energy intake and adiposity. Young children are often assumed to have the ability to self‐regulate eating behaviours in a way that protects against overconsumption. Therefore, a complementary approach to changing the food environment is to identify and cultivate ‘protective’ eating behaviours from an early age. But what is the evidence for children's capacity to self‐regulate food intake? And could cultivating self‐regulatory eating behaviours complement broader environmental approaches aimed at reducing unhealthy weight gain during childhood? This review considers these questions with a focus on three aspects of eating behaviour that challenge energy intake regulation and healthy growth: large portion sizes, eating speed and energy compensation abilities. As children get older and gain more experience in the food environment, individual self‐regulatory skills can be compromised by factors such as sustained exposure to large portion sizes and feeding practices that fail to take into account children's appetite cues. More research is required to understand the developmental trajectories of children's eating behaviours, but parents and caregivers have the opportunity to promote self‐regulatory eating from a young age. The success of individualised interventions that aim to empower children to recognise and respond to their own appetite signals will be contingent on broader improvements to the wider food environment.

Portion size reduction in preschool children: Snack reduction versus snack replacement

Portion size reduction in preschool children: Snack reduction versus snack replacement

Editorial and News

Editorial and News

Restructuring physical micro-environments to reduce the demand for meat: a systematic review and qualitative comparative analysis

SummaryBackgroundReducing meat consumption could help to protect the natural environment and promote population health. Interventions restructuring physical micro-environments might help to change habitual behaviour. We synthesised the scientific evidence pertaining to whether, and which, interventions restructuring physical micro-environments effectively reduce the demand for meat.MethodsWe did a systematic review of quantitative studies evaluating the effectiveness of interventions restructuring physical micro-environments to reduce the demand for meat. We identified relevant records by searching six electronic databases (CAB s, Embase, PsycINFO, Science Citation Index, MEDLINE, and Dissertations & Theses) on Aug 31, 2017, contacting experts, screening publicly accessible online resources, and searching references. We included studies that evaluated the effectiveness of interventions restructuring physical micro-environments to reduce the demand for meat, defined as the actual or intended consumption, purchase, or selection of meat in real or virtual environments. We extracted data pertaining to the study samples, the interventions, and meat demand at the follow-up closest to intervention completion and at the longest follow-up, with the former representing our primary outcome. We synthesised data narratively and did a qualitative comparative analysis to identify configurations of intervention characteristics associated with, and those not found to be associated with, significant reductions in meat demand. Our Systematic Review is registered with PROSPERO, number CRD42017081532.ResultsOf 10 733 titles and abstracts screened for eligibility, we assessed 60 full papers and included 14 papers reporting on 18 studies with 22 intervention conditions. Three interventions reducing the portion size of meat servings reduced meat consumption in randomised trials. Three interventions providing meat alternatives with supporting educational material were associated with reduced meat demand in pre-post design studies. Three of four interventions altering the sensory properties (eg, visual presentation) of meat or meat alternatives at point of purchase reduced meat demand in randomised trials. Four interventions repositioning meat products to be less prominent at point of purchase were associated with lower meat demand, but only two such interventions reached statistical significance in a randomised trial and a multiple treatment reversal design. Only one of five interventions manipulating the description of meat or meat alternatives at point of purchase was associated with lower meat demand in a multiple treatment reversal design. Evidence from randomised trials evaluating a pricing intervention or interventions restructuring several aspects of micro-environments was too scarce or inconsistent to be conclusive. The results from our qualitative comparative analysis supported the findings of this narrative synthesis.InterpretationSome interventions restructuring physical micro-environments could help to promote lower demand for meat. Interventions reducing portion sizes of meat servings, providing meat alternatives, or changing the sensory properties of meat and meat alternatives at point of purchase offered the most promise in the context of experimental studies.FundingNone.

An evaluation of the interactions among household economies, human health, and wildlife hunting in the Lac Alaotra wetland complex of Madagascar

In Madagascar, wildlife conservation and human food security and nutrition are deeply interconnected as many people rely on wild foods for sustenance. The Lac Alaotra wetland complex is an ecoregion which is indispensable to both the future food security of Madagascar’s people and the conservation of its endemic wildlife. The region is Madagascar’s largest rice production area, providing thousands of tons of rice and fish to the residents of one of the world’s least food secure nations. The wetland complex also provides habitat to numerous threatened species, including two Critically Endangered mammals found only in the Lac Alaotra wetland complex. Environmental managers must understand how people affect their local environment and how the environment, in turn, affects these people, their livelihoods, and their motivations for future natural resource use. Without an adequate understanding of the complex interactions of local people and their natural environment, it will be impossible to prevent, mitigate, or adapt to future unwanted changes in this complex social-ecological system. We used health assessments of 1 953 residents and semistructured interviews of members of 485 households in 1 9 communities within the Lac Alaotra wetland complex to investigate human-environmental interactions (including current natural resource use and hunting, and how these behaviors affect local economies and human wellbeing). Our team found that, while rates of wildlife consumption were very low throughout the region, the members of 485 surveyed households ate 975 mammals in 2013, including at least 1 6 Alaotra gentle lemurs. Thirteen percent of households had consumed wildlife in 201 3 and less than 1% of hunted wildlife was sold. Employment rates and annual income were both higher than other regions in Madagascar, and food costs were comparatively low. Nevertheless, 98% of households experienced food insecurity, and coping mechanisms (e.g., reducing portion sizes) appear to disproportionately affect young children and non-working members of households. Half of households did not receive the minimum recommended kilocalories per person per day. We found high rates of child malnutrition consistent with national rural statistics. While wildlife consumption does not appear to have significant economic or health benefits in the communities in the Alaotra wetland complex, high food insecurity significantly increased the number of forest and marshland mammals eaten by households. To improve child nutrition and wildlife conservation, we recommend targeted interventions that improve food security.

Impact of reducing portion sizes in worksite cafeterias: a stepped wedge randomised controlled pilot trial

BackgroundReducing the portion sizes of foods available in restaurants and cafeterias is one promising approach to reducing energy intake, but there is little evidence of its impact from randomised studies in field settings. This study aims to i. examine the feasibility and acceptability, and ii. estimate the impact on energy purchased, of reducing portion sizes in worksite cafeterias.MethodsNine worksites in England were recruited to reduce by at least 10% the portion sizes of foods available in their cafeterias from targeted categories (main meals, sides, desserts, cakes). In a stepped wedge randomised controlled pilot trial, each site was randomised to a date of implementation, staggered fortnightly, following a baseline period of four weeks. Impact on energy purchased was analysed using generalised linear mixed modelling. We also assessed feasibility, acceptability, and fidelity of intervention implementation.ResultsData from six of the nine randomised sites were analysed, with three sites excluded for not providing sufficient data and/or not implementing the intervention. The extent to which the intervention was implemented varied by site, with between 6 and 49% of products altered within targeted categories. Feedback following the intervention suggested it was broadly acceptable to customers and cafeteria staff. For the primary outcome of daily energy (kcal) purchased from intervention categories, there was no statistically significant change when data from all six sites were pooled: percentage change − 8.9% (95% CI: -16.7, − 0.4; p = 0.081). Each of these six sites showed reductions in energy purchased, ranging from − 15.6 to − 0.3%, which were borderline statistically significant at two sites (respective percentage changes (95% CIs): − 15.6% (− 26.7, − 2.8); − 14.0% (− 25.0, − 1.2)). Secondary outcome data are suggestive of a compensatory increase in energy purchased from food categories not targeted by the intervention, with no overall effect observed on energy purchased across all categories.ConclusionsThe results of this pilot trial suggest that reducing portion sizes could be effective in reducing energy purchased and consumed from targeted food categories, and merits investigation in a larger trial. Future studies will need to address factors that prevented optimal implementation including site dropout and application across a limited range of products.Trial Registration(ISRCTN52923504). Registered on 20th September 2016.

Meeting the food waste challenge in higher education

PurposeFood waste represents a major sustainability challenge with environmental, economic, social and health implications. Institutions of higher education contribute to generating food waste while serving as models in championing sustainability solutions. An experiential learning project was implemented as part of two university courses in a buffet-style university dining hall with the objective to reduce food waste while building student capacity to contribute to transformational food system change.Design/methodology/approachPartnerships were developed with university dining services. Students were trained to conduct a needs assessment in a university dining hall through food waste measurements. Students were facilitated through the process of applying baseline data on food waste to design, implement and evaluate a multi-component food waste intervention that consisted of offering reduced portion sizes, use of smaller serving utensils and educational messaging. Participant reflections were elicited to evaluate the effectiveness of the experiential learning experience.FindingsThe food waste intervention led to a 17 per cent reduction in total food waste, with a large portion of waste attributed to post-consumer plate waste. While the reduction in food waste was not statistically significant, it highlights the potential for food service operations to address food waste through reduction techniques while providing students an experiential opportunity that meets multiple learning objectives including systems thinking, collaboration and motivation for leading change in the food system.Originality/valueThis study highlights the opportunity of building student capacity to address sustainability challenges through an experiential learning model for reducing food waste in an institutional setting that other educators can adapt.

The effect of a portion size intervention on French fries consumption, plate waste, satiety and compensatory caloric intake: an on-campus restaurant experiment

BackgroundOne of the driving factors of dietary overconsumption throughout the last decennia is the increase of food portion sizes. Larger portions induce higher daily energy intake, so reducing portion size may reduce intake of excess calories. However, real-life studies about the effects of portion size reduction are lacking. Therefore, this study examined the effect of a French fries portion size reduction on French fries consumption, French fries plate waste, satiety and caloric intake during the subsequent afternoon among university students and employees in a Belgian on-campus restaurant setting. Moreover, this study evaluated consumers’ perception about the portion size reduction.MethodsThe study took place over a two-time (i.e. baseline and intervention week) 4-day period (Tuesday–Friday) in the on-campus restaurant where ±1200 meals are served every day. French fries’ portions were reduced by 20% by replacing the usual porcelain bowl served during the baseline week (±200 g) with smaller volume paper bags during the intervention week (±159 g) in a pre-post real-life experiment. French fries consumption and plate waste were measured in 2056 consumers at baseline and 2175 consumers at intervention. Additionally, interviews were conducted directly after lunch and again between 4 and 6 p.m. on the same day to assess satiety and caloric intake at pre and post in a small subsample of both French fries consumers (n = 19) and non-French fries consumers (n = 14). Post-intervention, the same subsample was interviewed about their perception of the portion size reduction (n = 28).ResultsTotal French fries intake decreased by 9.1%, and total plate waste decreased by 66.4%. No differences were found in satiety or caloric intake between baseline and intervention week among the French fries’ consumers. The majority (n = 24, 86%) of French fries consumers noticed the reduction in portion size during the intervention. Although most participants (n = 19, 68%) perceived the reduced portion size as sufficient, only a minority of participants (n = 9, 32%) indicated post-intervention that they would agree with a permanent implementation.ConclusionsReducing portion size may lead to reduced caloric intake, without changing perceived levels of satiety.

Will reduced portion size compromise restaurant customer’s value perception?

The restaurant industry’s increased portion sizes have led to accusations that they contribute to food overconsumption. Reducing excessive food portions in restaurants, however, may be considered risky by foodservice operators concerned about consumers’ perceived value of the food. Two quasi-experiments were conducted examining how changes in portion and plate size would affect restaurant consumers’ perceived reasonable price of food and their willingness to pay. A two-by-two, between-subject factorial design was used in study 1 (n = 101) with plate size (small & medium) and portion size (regular & reduced) as independent variables. Study 2 used a between subject design with three experimental conditions: large portion, medium portion, and small portion (n = 71). Results showed that the impact of a reduced portion size on consumer’s perceived value of the food depended on the consumers’ perceived quality of the food and their purchase intention.

Controlled testing of novel portion control plate produces smaller self-selected portion sizes compared to regular dinner plate

BackgroundObesity is a global health crisis, and portion control is a key method for reducing excess body weight. Given consumers’ familiarity with large portion sizes, reducing portion sizes can be difficult. Smaller plates are often recommended to reduce portion sizes and appear to reduce portion sizes. However, there are no studies evaluating dishes specifically designed to facilitate portion control. The aim of the present study was to validate the efficacy of a novel portion control plate inspired by the Ebbinghaus and Delboeuf visual illusions to promote serving smaller portions compared to a larger dinner plate.MethodsIn two studies with a total of 110 university students, we determined whether the use of the portion control plate would result in smaller food portions compared to a larger dinner plate. The portion control plate was smaller and incorporated portion size indicators. Study 1 used instructions from My Plate based on plate ratios (e.g., “the USDA recommends filling half your plate with vegetables”) and study 2 used absolute portion size recommendations (e.g., “1 cup of vegetables”).ResultsThe portion control plate produced smaller self-selected servings in both studies. However, the servings of vegetables selected were smaller than recommended portion sizes for both the portion control plate and the regular dinner plate.ConclusionsPortion control plates have the potential to reduce self-selected portion sizes. Future research should include studies in a broader range of ages and clinical trials of portion control dishes for weight loss.