What Everyone Else Is Eating: A Systematic Review and Meta-Analysis of the Effect of Informational Eating Norms on Eating Behavior

A Mediation Analysis of Mothers' Dietary Intake: The Entre Familia: Reflejos de Salud Randomized Controlled Trial

AIMS

Examine intervention effects among mothers involved in a healthy eating randomized controlled trial. Furthermore, examine the mediating roles of individual and familial influences on observed outcomes.

METHODS

Between 2009 and 2011, 361 families were recruited; half were assigned to an 11-session community health worker-delivered family-based intervention targeting Spanish-speaking Latino families in Imperial County, California. The intervention was delivered over a 4-month period. Home visits and telephone calls were delivered approximately weekly, with tapering near the end of the intervention to promote independence from the promotora. In this article, mothers' self-reported dietary intake was the primary outcome. Evaluation measures were taken at baseline, 4 months, and 10 months.

RESULTS

Daily servings of fruits were higher among intervention versus control mothers (mean = 1.86 vs. mean = 1.47; effect size [ES] = 0.22) at 10 months post-baseline. Mothers in the intervention versus control condition also reported consuming a lower percent energy from fat (mean = 30.0% vs. 31.0%; ES = 0.30) and a higher diet quality (mean = 2.93 vs. mean = 2.67; ES = 0.29). Mediators of improvements were behavioral strategies to increase fiber and lower fat intake, family support for vegetable purchasing, and decreased unhealthy eating behaviors and perceived family barriers to healthy eating.

DISCUSSION AND CONCLUSION

Family-based behavioral interventions are effective for changing the skills and family system needed to improve diet among Latina mothers. Health care providers and other practitioners are encouraged to target skill development and fostering a socially supportive environment.

Interventions to promote healthy eating choices when dining out: A systematic review of reviews

PURPOSE

To synthesize review research pertaining to the effectiveness of interventions in dining-out settings to reduce food/calorie consumption.

METHODS

A rapid review methodology was employed to focus on synthesized research. A comprehensive search for peer-reviewed systematic reviews from 2010 to 2015 yielded 1,847 citations. Following screening, ten systematic reviews were included.

RESULTS

The 10 included systematic reviews identified 183 primary studies evaluating evidence in three behavioural intervention areas: social models/norms, manipulation of size, and provision of health information. Three systematic reviews evaluating the use of social models/norms found this was an effective intervention for influencing food intake. Five systematic reviews that assessed manipulation of portion/dishware/cutlery size found a small-to-moderate effect on food consumption. Three systematic reviews looked at the provision of health information, which was not effective alone; however, in combination with contextual or interpretive material such as traffic lights or exercise equivalence, this was shown to reduce calorie consumption. One systematic review covered two topic areas.

CONCLUSIONS

The results indicate that policies or interventions that aim to improve healthy choices or consumption when dining out would benefit from harnessing social norms and positive positioning of social identity. Furthermore, provision of health information should always be accompanied by an interpretative guide, such as traffic lights. Manipulation of plate/portion/cutlery size may be effective; however, the effect size is small and further research is required to investigate whether this effect is retained in overweight or obese populations. Statement of contribution What is already known on this subject? Eating behaviours (food choices, consumption) have played a role in the obesity epidemic. Behavioural 'nudges' have tried to increase healthier eating choices. What does this study add? Social norms and modelling have a strong influence in both directions on how much people consume. Provision of nutritional information needs to be paired with interpretative aids (e.g., traffic lights). Manipulation of portion size is less effective in overweight populations.

Social approval bias in self-reported fruit and vegetable intake after presentation of a normative message in college students

OBJECTIVE

To determine the accuracy of self-reported data regarding Fruit and Vegetable (FV) intake in college students at Utah State University after being presented with a descriptive normative message.

INTERVENTION

Participants (N = 167) were recruited from general education courses and asked to complete a baseline survey containing a FV screener from the National Cancer Institute. They were then randomized to receive one of four messages one week after the initial survey and asked to immediately complete the same FV screener. The Control group received no FV message. The Recommendation group received a message that the recommendation for FV is 4-5 cups per day. The two normative groups received a message that either 80% of students ate more (Low) or less (High) FV than they did, regardless of actual intake, in addition to the recommended intake.

ANALYSIS

Repeated measures ANOVA was used to assess differences in reported FV intake and perceived FV intake of peers between the first and second assessment.

RESULTS AND CONCLUSIONS

Those receiving the message that they were in the lowest 20th percentile of intake reported a half-cup increase in self-reported FV intake and a one-cup increase in perception of peers' intake (p = 0.037 and p=<0.001, respectively). No significant differences were observed in other groups. These results indicate that normative messaging may influence self-reported FV intake and perception of peer intake of college students when this message indicates that the participant is in the lowest percentile of their peers.

Using a descriptive social norm to increase vegetable selection in workplace restaurant settings

Objective: Recent work has shown that exposure to social norm messages may enhance the consumption of vegetables. However, the majority of this work has been conducted in laboratories, often with student populations. Little is known about whether this approach can be successfully used in other contexts. In this study, a poster featuring a message based on social norms was tested to examine whether it could increase and maintain the purchase of meals with vegetables in workplace restaurants. Method: A pretest–posttest design with 3 phases was used in 3 workplace restaurants in the United Kingdom. The first 2 weeks formed the preintervention phase, the second 2 weeks the intervention phase, and the last 2 weeks the postintervention phase. During the intervention phase only, posters containing a social norm message relaying information about vegetable purchases of other diners were placed in each restaurant. The main outcome measure was the percentage of meals purchased with vegetables, which was analyzed using Pearson’s chi-squared test. Results: Participants were judged to be male (57%), not overweight (75%), and under the age of 60 (98%). The intervention was positively associated with the percentage of meals purchased with vegetables: baseline versus intervention (60% vs. 64% of meals purchased with vegetables; p < .01); intervention versus postintervention (64% vs. 67% of meals purchased with vegetables; p < .01); and baseline versus postintervention (60% vs. 67% of meals purchased with vegetables; p < .001). Conclusions: Social norm messages may increase the purchase of vegetables in workplace settings.

Understanding perceived determinants of nurses' eating and physical activity behaviour: a theory-informed qualitative interview study

BACKGROUND

Unhealthy eating and physical activity behaviours are common among nurses but little is known about determinants of eating and physical activity behaviour in this population. The present study used a theoretical framework which summarises the many possible determinants of different health behaviours (the Theoretical Domains Framework; TDF) to systematically explore the most salient determinants of unhealthy eating and physical activity behaviour in hospital-based nurses.

METHODS

Semi-structured qualitative interviews based on the TDF were conducted with nurses (n = 16) to explore factors that behavioural theories suggest may influence nurses' eating and physical activity behaviour. Important determinants of the target behaviours were identified using both inductive coding (of categories emerging from the data) and deductive coding (of categories derived from the TDF) of the qualitative data.

RESULTS

Thirteen of the fourteen domains in the TDF were found to influence nurses' eating and physical activity behaviour. Within these domains, important barriers to engaging in healthy eating and physical activity behaviour were shift work, fatigue, stress, beliefs about negative consequences, the behaviours of family and friends and lack of planning. Important factors reported to enable engagement with healthy eating and physical activity behaviours were beliefs about benefits, the use of self-monitoring strategies, support from work colleagues, confidence, shift work, awareness of useful guidelines and strategies, good mood, future holidays and receiving compliments.

CONCLUSIONS

This study used a theory-informed approach by applying the TDF to identify the key perceived determinants of nurses' eating and physical activity behaviour. The findings suggest that future efforts to change nurses' eating and physical activity behaviours should consider targeting a broad range of environmental, interpersonal and intrapersonal level factors, consistent with a socio-ecological perspective.

The social image of food: Associations between popularity and eating behavior

One factor that determines what we eat and why we eat is our social environment. In the present research, two online studies examined the relationship between food intake and social images. Specifically, the present research assessed the relationship between the food intake university students ascribed to peers who varied in popularity and own self-reported food intake, and whether this relationship was moderated by identification with the peer group. Participants (N = 97 in Study 1; N = 402 in Study 2) were randomly presented with one of four (Study 1) or two of eight (Study 2) vignettes describing a popular or unpopular student (male or female) from their university without receiving any information about the peer's eating behavior. Subsequently, healthy and unhealthy eating ascribed to the peers and own self-reported eating behavior were assessed. Results indicated that popular peers were perceived to eat more healthily than unpopular peers. Moreover, eating behavior ascribed to popular peers were associated with own healthy and unhealthy eating. Importantly, the relationship between healthy eating behavior ascribed to popular peers and own healthy eating behavior was moderated by identification with the student group - the more participants identified with their peers, the more their own eating was aligned with the healthy eating ascribed to a popular peer. Hence, the popularity of others seems to shape perceptions of the food they eat and may facilitate healthy eating via social influence.

Current findings on the role of oxytocin in the regulation of food intake

In the face of the alarming prevalence of obesity and its associated metabolic impairments, it is of high basic and clinical interest to reach a complete understanding of the central nervous pathways that establish metabolic control. In recent years, the hypothalamic neuropeptide oxytocin, which is primarily known for its involvement in psychosocial processes and reproductive behavior, has received increasing attention as a modulator of metabolic function. Oxytocin administration to the brain of normal-weight animals, but also animals with diet-induced or genetically engineered obesity reduces food intake and body weight, and can also increase energy expenditure. Up to now, only a handful of studies in humans have investigated oxytocin's contribution to the regulation of eating behavior. Relying on the intranasal pathway of oxytocin administration, which is a non-invasive strategy to target central nervous oxytocin receptors, these experiments have yielded some promising first results. In normal-weight and obese individuals, intranasal oxytocin acutely limits meal intake and the consumption of palatable snacks. It is still unclear to which extent - or if at all - such metabolic effects of oxytocin in humans are conveyed or modulated by oxytocin's impact on cognitive processes, in particular on psychosocial function. We shortly summarize the current literature on oxytocin's involvement in food intake and metabolic control, ponder potential links to social and cognitive processes, and address future perspectives as well as limitations of oxytocin administration in experimental and clinical contexts.

The Role of Technology in Healthy Living Medicine

Health care consumers are taking control of their health information and desire a greater role in managing their health. Approximately 77% of Americans now own a smartphone and the use of health apps have doubled over the past two years. These effects are particularly notable in patients with chronic disease, now representing half the adult population and responsible for 86% of United States health care (HC) costs and 70% of deaths. New opportunities exist as a result of recent advances in home-based wireless devices, apps, wearables, and interactive systems enabling health delivery systems to monitor, advise and treat disease near real time and engage patients in healthy living medicine. These technologies will provide a new framework for patient engagement and care delivery that will enhance clinical outcomes and generate precision interventions that ultimately reduce HC costs.

Perceived eating norms and children's eating behaviour: An informational social influence account

There is initial evidence that beliefs about the eating behaviour of others (perceived eating norms) can influence children's vegetable consumption, but little research has examined the mechanisms explaining this effect. In two studies we aimed to replicate the effect that perceived eating norms have on children's vegetable consumption, and to explore mechanisms which may underlie the influence of perceived eating norms on children's vegetable consumption. Study 1 investigated whether children follow perceived eating norms due to a desire to maintain personal feelings of social acceptance. Study 2 investigated whether perceived eating norms influence eating behaviour because eating norms provide information which can remove uncertainty about how to behave. Across both studies children were exposed to vegetable consumption information of other children and their vegetable consumption was examined. In both studies children were influenced by perceived eating norms, eating more when led to believe others had eaten a large amount compared to when led to believe others had eaten no vegetables. In Study 1, children were influenced by a perceived eating norm regardless of whether they felt sure or unsure that other children accepted them. In Study 2, children were most influenced by a perceived eating norm if they were eating in a novel context in which it may have been uncertain how to behave, as opposed to an eating context that children had already encountered. Perceived eating norms may influence children's eating behaviour by removing uncertainty about how to behave, otherwise known as informational social influence.

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Mechanisms underlying the influence of perceived eating norms were examined.

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Perceived eating norms influenced children's vegetable consumption.

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Perceived eating norms may act as a form of informational social influence on consumption.

Local descriptive body weight and dietary norms, food availability, and 10-year change in glycosylated haemoglobin in an Australian population-based biomedical cohort

BACKGROUND

Individual-level health outcomes are shaped by environmental risk conditions. Norms figure prominently in socio-behavioural theories yet spatial variations in health-related norms have rarely been investigated as environmental risk conditions. This study assessed: 1) the contributions of local descriptive norms for overweight/obesity and dietary behaviour to 10-year change in glycosylated haemoglobin (HbA1c), accounting for food resource availability; and 2) whether associations between local descriptive norms and HbA1c were moderated by food resource availability.

METHODS

HbA1c, representing cardiometabolic risk, was measured three times over 10 years for a population-based biomedical cohort of adults in Adelaide, South Australia. Residential environmental exposures were defined using 1600 m participant-centred road-network buffers. Local descriptive norms for overweight/obesity and insufficient fruit intake (proportion of residents with BMI ≥ 25 kg/m2 [n = 1890] or fruit intake of <2 serves/day [n = 1945], respectively) were aggregated from responses to a separate geocoded population survey. Fast-food and healthful food resource availability (counts) were extracted from a retail database. Separate sets of multilevel models included different predictors, one local descriptive norm and either fast-food or healthful food resource availability, with area-level education and individual-level covariates (age, sex, employment status, education, marital status, and smoking status). Interactions between local descriptive norms and food resource availability were tested.

RESULTS

HbA1c concentration rose over time. Local descriptive norms for overweight/obesity and insufficient fruit intake predicted greater rates of increase in HbA1c. Neither fast-food nor healthful food resource availability were associated with change in HbA1c. Greater healthful food resource availability reduced the rate of increase in HbA1c concentration attributed to the overweight/obesity norm.

CONCLUSIONS

Local descriptive health-related norms, not food resource availability, predicted 10-year change in HbA1c. Null findings for food resource availability may reflect a sufficiency or minimum threshold level of resources such that availability poses no barrier to obtaining healthful or unhealthful foods for this region. However, the influence of local descriptive norms varied according to food resource availability in effects on HbA1c. Local descriptive health-related norms have received little attention thus far but are important influences on individual cardiometabolic risk. Further research is needed to explore how local descriptive norms contribute to chronic disease risk and outcomes.

The Longitudinal Associations between Perceived Descriptive Peer Norms and Eating and Drinking Behavior: An Initial Examination in Young Adults

Experimental and cross-sectional studies indicate that perceptions of the eating and drinking behavior of one's peers (perceived descriptive peer norms) are associated with the types, frequency and quantity of food, and beverages a person chooses to consume. At present, we know very little about the longitudinal association between perceived descriptive peer norms and future eating or drinking behavior. In this study, we examined whether perceived descriptive peer norms for different food/beverage types predicted frequency of consumption of food/beverages in university students. Three hundred and forty participants completed measures at baseline and follow-up for frequency of consumption of cakes/pastries, sugar containing beverages, and alcoholic beverages, as well as measures of perceived descriptive peer norms at both time points. Perceived descriptive peer norms predicted consumption of pastries/cakes at follow up when controlling for changes in these perceptions over time; believing that one's peers frequently consumed cakes/pastries was associated with an increased frequency of consumption over time, although the magnitude of this effect was small. There was no significant association between perceived descriptive peer norms and changes in frequency of consumption of sugar containing beverages or alcohol over time. In the present longitudinal study of young adults, beliefs about how often one's peers eat or drink specific food and beverages types had limited effect on future eating and drinking behavior.

Variations in Weight Stigma Concerns

Over the past 40 years, obesity rates in the United States have grown significantly; these rates have not grown uniformly across the United States (18 of the 20 counties with the highest obesity rates are located in the South). Obesity increases cardiovascular disease risk factors and new research has highlighted the negative psychological effects of obesity, known as weight stigma, including decreased selfcontrol resources, over eating, and exercise avoidance. The primary objective of this study was to determine if weight stigma concerns varied regionally and if social behaviors influenced this variation. In two studies, we collected cross-sectional data from participants in the United States including height and weight, weight stigma concerns, and perception of friends' preoccupation with weight and dieting. We also collected each participant's home zip code which was used to locate local obesity rate. We established differences in the relationship between body mass index and weight stigma concerns by local county obesity rate and showed that perceived friend preoccupation with weight and dieting mediated this relationship for individuals in low and medium obesity rate counties. For individuals living in United States counties with lower levels of obesity, increases in personal body mass index leads to increased weight stigma concerns due to an increase in perceived friend preoccupation with weight and dieting. These results indicate that relationships between body mass index, weight stigma concerns, and social networks vary significantly for subpopulations throughout the United States.

The persistence of and resistance to social norms regarding the appropriate amount to Eat: A preliminary investigation

We conducted a preliminary investigation on the resistance to, and persistence of, social influence regarding the appropriate amount to eat, defined in terms of eating an amount similar to that eaten by a confederate. Participants ate pizza both alone and in the presence of remote confederates presenting either a high or low eating norm. In the portion of the experiment examining resistance to social influence, participants given an initial opportunity to form a personal eating norm by eating alone for one session in the absence of social influence were no more resistant to low eating norms than were those who had no such opportunity; however, those who ate alone for two or three prior sessions did show resistance. For the high eating norm, it took three eating alone sessions to create resistance. In the portion of the experiment examining persistence of social influence, when participants ate alone following a session with norm-setting remote confederates, the effect of the social influence persisted. However, the persistence effect varied by norm and weakened over time. Participants modeled a low eating norm for only one additional session and the size of the effect was markedly weaker. By contrast, the high norm persisted for all of the remaining sessions. Thus, individuals' social influence histories can affect their eating.

Social Norms Shift Preferences for Healthy and Unhealthy Foods

This research investigated whether people change their food preferences and eating behavior in response to health-based social norms. One hundred twenty participants rated a series of healthy and unhealthy food images. After each rating, participants sometimes viewed a rating that ostensibly represented the average rating of previous participants. In fact, these average ratings were manipulated to convey a particular social norm. Participants either saw average ratings that favored healthy foods, favored unhealthy foods, or did not see any average ratings. Participants then re-rated those same food images after approximately ten minutes and again three days later. After the norm manipulation, participants were given the chance to take as many M&Ms as they wanted. Participants exposed to a healthy social norm consistently reported lower preferences for unhealthy foods as compared to participants in the other two conditions. This preference difference persisted three days after the social norm manipulation. However, health-based social norm manipulations did not influence the amount of M&Ms participants took. Although health-based social norm manipulations can influence stated food preferences, in this case they did not influence subsequent eating behavior.

Incident Type 2 Diabetes Risk is Influenced by Obesity and Diabetes in Social Contacts: a Social Network Analysis

BACKGROUND

Obesity and diabetes family history are the two strongest risk factors for type 2 diabetes (T2D). Prior work shows that an individual's obesity risk is associated with obesity in social contacts, but whether T2D risk follows similar patterns is unknown.

OBJECTIVE

We aimed to estimate the relationship between obesity or diabetes in an individual's social contacts and his/her T2D risk. We hypothesized that obesity and diabetes in social contacts would increase an individual's T2D risk.

DESIGN

This was a retrospective analysis of the community-based Framingham Offspring Study (FOS).

PARTICIPANTS

FOS participants with T2D status, height and weight, and at least one social contact were eligible for this study (n = 4797 at Exam 1). Participants' interpersonal ties, cardiometabolic and demographic variables were available at eight exams from 1971 to 2008, and a T2D additive polygenic risk score was measured at the fifth exam.

MAIN MEASURES

Primary exposures were T2D (fasting glucose ≥ 7 mmol/L or taking diabetes medications) and obesity status (BMI ≥ 30 kg/m(2)) of social contacts at a prior exam. Primary outcome was incident T2D in participants.

KEY RESULTS

Incident T2D was associated with having a social contact with diabetes (OR 1.32, p = 0.004) or with obesity (OR 1.21, p = 0.004). In stratified analyses, incident T2D was associated with diabetes in siblings (OR 1.64, p = 0.001) and obesity in spouses (OR 1.54, p = 0.0004). The associations between diabetes and obesity in social contacts and an individual's incident diabetes risk were stronger in individuals with a high diabetes genetic risk score.

CONCLUSIONS

T2D and obesity in social contacts, particularly siblings and spouses, were associated with an individual's risk of incident diabetes even after accounting for parental T2D history. Assessing risk factors in an individual's siblings and spouses can inform T2D risk; furthermore, social network based lifestyle interventions involving spouses and siblings might be a novel T2D prevention approach.

Relationship between Parental Feeding Practices and Neural Responses to Food Cues in Adolescents

Social context, specifically within the family, influences adolescent eating behaviours and thus their health. Little is known about the specific mechanisms underlying the effects of parental feeding practices on eating. We explored relationships between parental feeding practices and adolescent eating habits and brain activity in response to viewing food images. Fifty- seven adolescents (15 with type 2 diabetes mellitus, 21 obese and 21 healthy weight controls) underwent fMRI scanning whilst viewing images of food or matched control images. Participants completed the Kids Child Feeding Questionnaire, the Childrens’ Dutch Eating Behaviour Questionnaire (DEBQ) and took part in an observed meal. Parents completed the Comprehensive Feeding Practices Questionniare and the DEBQ. We were particularly interested in brain activity in response to food cues that was modulated by different feeding and eating styles. Healthy-weight participants increased activation (compared to the other groups) to food in proportion to the level of parental restriction in visual areas of the brain such as right lateral occipital cortex (LOC), right temporal occipital cortex, left occipital fusiform gyrus, left lateral and superior LOC. Adolescents with type 2 diabetes mellitus had higher activation (compared to the other groups) with increased parental restrictive feeding in areas relating to emotional control, attention and decision-making, such as posterior cingulate, precuneus, frontal operculum and right middle frontal gyrus. Participants with type 2 diabetes mellitus also showed higher activation (compared to the other groups) in the left anterior intraparietal sulcus and angular gyrus when they also reported higher self restraint. Parental restriction did not modulate food responses in obese participants, but there was increased activity in visual (visual cortex, left LOC, left occipital fusiform gyrus) and reward related brain areas (thalamus and parietal operculum) in response to parental teaching and modelling of behaviour. Parental restrictive feeding and parental teaching and modelling affected neural responses to food cues in different ways, depending on motivations and diagnoses, illustrating a social influence on neural responses to food cues.

The Role of Social Norms in the Portion Size Effect: Reducing Normative Relevance Reduces the Effect of Portion Size on Consumption Decisions

People typically eat more from large portions of food than from small portions. An explanation that has often been given for this so-called portion size effect is that the portion size acts as a social norm and as such communicates how much is appropriate to eat. In this paper, we tested this explanation by examining whether manipulating the relevance of the portion size as a social norm changes the portion size effect, as assessed by prospective consumption decisions. We conducted one pilot experiment and one full experiment in which participants respectively indicated how much they would eat or serve themselves from a given amount of different foods. In the pilot (N = 63), we manipulated normative relevance by allegedly basing the portion size on the behavior of either students of the own university (in-group) or of another university (out-group). In the main experiment (N = 321), we told participants that either a minority or majority of people similar to them approved of the portion size. Results show that in both experiments, participants expected to serve themselves and to eat more from larger than from smaller portions. As expected, however, the portion size effect was less pronounced when the reference portions were allegedly based on the behavior of an out-group (pilot) or approved only by a minority (main experiment). These findings suggest that the portion size indeed provides normative information, because participants were less influenced by it if it communicated the behaviors or values of a less relevant social group. In addition, in the main experiment, the relation between portion size and the expected amount served was partially mediated by the amount that was considered appropriate, suggesting that concerns about eating an appropriate amount indeed play a role in the portion size effect. However, since the portion size effect was weakened but not eliminated by the normative relevance manipulations and since mediation was only partial, other mechanisms may also play a role.

Seasonal cycles in food purchases and changes in BMI among South Africans participating in a health promotion programme

Objective

Improving diet quality is a key factor for promoting population health. Social norms can support or undermine these efforts. The present study aimed to investigate the relationship between seasonal variation in food purchases and BMI.

Design

The study population comprises members of a South African health promotion programme. Data come from scanner data of food purchases by 400 000 enrolled households at supermarkets and repeated individual surveys (about 500 000 participants) between 2009 and 2013.

Results

Members in the health promotion programme spent 16·7 % of total food expenditure on nutritionally undesirable foods (sugar-sweetened beverages, candy, ice cream, etc.) and 24·7 % on healthy foods (fruit/vegetables, whole grains, non-fat dairy, etc.). Fruits and vegetables accounted for 13·5 % of purchases (half of all healthy food spending). Yet there were pronounced seasonal variations, with December being the peak month for unhealthy food purchases, which were 40 % higher than in January. This holiday peak was associated with short-term weight gain, but average body mass did not revert to pre-holiday levels. From 2009 to 2013, respondents gained about 0·13 BMI units per year (0·43 kg for men, 0·30 for women). From November to January alone, the increase was 0·1 BMI units for men (0·35 kg) and 0·8 BMI units for women (0·20 kg).

Conclusions

Purchases of nutritionally undesirable foods peak in December and are accompanied by weight gain from November to January. Despite weight loss after January, the November to January weight gain accounts for 60–70 % of the annual gain.

Social norms and financial incentives to promote employees' healthy food choices: A randomized controlled trial

OBJECTIVE

Population-level strategies to improve healthy food choices are needed for obesity prevention. We conducted a randomized controlled trial of 2672 employees at the Massachusetts General Hospital who were regular customers of the hospital cafeteria with all items labeled green (healthy), yellow (less healthy), or red (unhealthy) to determine if social norm (peer-comparison) feedback with or without financial incentives increased employees' healthy food choices.

METHODS

Participants were randomized in 2012 to three arms: 1) monthly letter with social norm feedback about healthy food purchases, comparing employee to "all" and to "healthiest" customers (feedback-only); 2) monthly letter with social norm feedback plus small financial incentive for increasing green purchases (feedback-incentive); or 3) no contact (control). The main outcome was change in proportion of green-labeled purchases at the end of 3-month intervention. Post-hoc analyses examined linear trends.

RESULTS

At baseline, the proportion of green-labeled purchases (50%) did not differ between arms. At the end of the 3-month intervention, the percentage increase in green-labeled purchases was larger in the feedback-incentive arm compared to control (2.2% vs. 0.1%, P=0.03), but the two intervention arms were not different. The rate of increase in green-labeled purchases was higher in both feedback-only (P=0.04) and feedback-incentive arms (P=0.004) compared to control. At the end of a 3-month wash-out, there were no differences between control and intervention arms.

CONCLUSIONS

Social norms plus small financial incentives increased employees' healthy food choices over the short-term. Future research will be needed to assess the impact of this relatively low-cost intervention on employees' food choices and weight over the long-term.

TRIAL REGISTRATION

Clinical Trials.gov: NCT01604499.

Social networks and social support for healthy eating among Latina breast cancer survivors: implications for social and behavioral interventions

PURPOSE

Little is known about Latina breast cancer survivors' social networks or their perceived social support to achieve and maintain a healthy diet. This paper describes the social networks and perceived support for healthy eating in a sample of breast cancer survivors of predominantly Dominican descent living in New York City.

METHODS

Spanish-speaking Latina breast cancer survivors enrolled in a randomized controlled trial of a culturally tailored dietary intervention. Social networks were assessed using Cohen's Social Network Index and a modified General Social Survey Social Networks Module that included assessments of shared health promoting behaviors. Perceived social support from family and friends for healthy, food-related behaviors was assessed.

RESULTS

Participants' networks consisted predominantly of family and friends. Family members were more likely than other individuals to be identified as close network members. Participants were more likely to share food-related activities than exercise activities with close network members. Perceived social support for healthy eating was high, although perceived support from spouses and children was higher than support from friends. Despite high levels of perceived support, family was also identified as a barrier to eating healthy foods by nearly half of women.

CONCLUSIONS

Although friends are part of Latina breast cancer survivors' social networks, spouses and children may provide greater support for healthy eating than friends.

IMPLICATIONS FOR CANCER SURVIVORS

Involving family members in dietary interventions for Latina breast cancer survivors may tap into positive sources of support for women, which could facilitate uptake and maintenance of healthy eating behaviors.

Encouraging children to eat more fruit and vegetables: Health vs. descriptive social norm-based messages

Traditional intervention approaches to promote fruit and vegetable consumption outline the health benefits of eating fruit and vegetables. More recently, social norm-based messages describing the healthy eating habits of others have been shown to increase fruit and vegetable intake in adults. Here we report two experimental studies which investigated whether exposure to descriptive social norm-based messages about the behaviour of other children and health-based messages increased fruit and vegetable intake in young children. In both studies children were exposed to messages whilst playing a board-game. After exposure to the messages, children were able to consume fruit and vegetables, as well as high calorie snack foods. Although findings were inconsistent across the two individual studies, in a pooled analysis we found evidence that both health messages and descriptive social norm-based messages increased children's fruit and vegetable intake, relative to control condition messages (p < .05). Whether descriptive social norm-based messages can be used to promote meaningful changes to children's dietary behaviour warrants further study.

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Descriptive social norm-based and health messages were examined.

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Health messages increased fruit and vegetable intake.

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Descriptive social norm-based messages increased fruit and vegetable intake.

A call for research exploring social media influences on mothers' child feeding practices and childhood obesity risk

There is increasing interest in leveraging social media to prevent childhood obesity, however, the evidence base for how social media currently influences related behaviors and how interventions could be developed for these platforms is lacking. This commentary calls for research on the extent to which mothers use social media to learn about child feeding practices and the mechanisms through which social media influences their child feeding practices. Such formative research could be applied to the development and dissemination of evidence-based childhood obesity prevention programs that utilize social media. Mothers are identified as a uniquely important target audience for social media-based interventions because of their proximal influence on children's eating behavior and their high engagement with social media platforms. Understanding mothers' current behaviors, interests, and needs as they relate to their social media use and child feeding practices is an integral first step in the development of interventions that aim to engage mothers for obesity prevention. This commentary highlights the importance of mothers for childhood obesity prevention; discusses theoretical and analytic frameworks that can inform research on social media and mothers' child feeding practices; provides evidence that social media is an emerging context for social influences on mothers' attitudes and behaviors in which food is a salient topic; and suggests directions for future research.

Visual exposure to large and small portion sizes and perceptions of portion size normality: Three experimental studies

Portion sizes of many foods have increased in recent times. In three studies we examined the effect that repeated visual exposure to larger versus smaller food portion sizes has on perceptions of what constitutes a normal-sized food portion and measures of portion size selection. In studies 1 and 2 participants were visually exposed to images of large or small portions of spaghetti bolognese, before making evaluations about an image of an intermediate sized portion of the same food. In study 3 participants were exposed to images of large or small portions of a snack food before selecting a portion size of snack food to consume. Across the three studies, visual exposure to larger as opposed to smaller portion sizes resulted in participants considering a normal portion of food to be larger than a reference intermediate sized portion. In studies 1 and 2 visual exposure to larger portion sizes also increased the size of self-reported ideal meal size. In study 3 visual exposure to larger portion sizes of a snack food did not affect how much of that food participants subsequently served themselves and ate. Visual exposure to larger portion sizes may adjust visual perceptions of what constitutes a 'normal' sized portion. However, we did not find evidence that visual exposure to larger portions altered snack food intake.

Personality and Situation Predictors of Consistent Eating Patterns

INTRODUCTION

A consistent eating style might be beneficial to avoid overeating in a food-rich environment. Eating consistency entails maintaining a similar dietary pattern across different eating situations. This construct is relatively under-studied, but the available evidence suggests that eating consistency supports successful weight maintenance and decreases risk for metabolic syndrome and cardiovascular disease. Yet, personality and situation predictors of consistency have not been studied.

METHODS

A community-based sample of 164 women completed various personality tests, and 139 of them also reported their eating behaviour 6 times/day over 10 observational days. We focused on observations with meals (breakfast, lunch, or dinner). The participants indicated if their momentary eating patterns were consistent with their own baseline eating patterns in terms of healthiness or size of the meal. Further, participants described various characteristics of each eating situation.

RESULTS

Eating consistency was positively predicted by trait self-control. Eating consistency was undermined by eating in the evening, eating with others, eating away from home, having consumed alcohol and having undertaken physical exercise. Interactions emerged between personality traits and situations, including punishment sensitivity, restraint, physical activity and alcohol consumption.

CONCLUSION

Trait self-control and several eating situation variables were related to eating consistency. These findings provide a starting point for targeting interventions to improve consistency, suggesting that a focus on self-control skills, together with addressing contextual factors such as social situations and time of day, may be most promising. This work is a first step to provide people with the tools they need to maintain a consistently healthy lifestyle in a food-rich environment.

Influence of Parenting Practices on Eating Behaviors of Early Adolescents during Independent Eating Occasions: Implications for Obesity Prevention

Among early adolescents (10-14 years), poor diet quality along with physical inactivity can contribute to an increased risk of obesity and associated biomarkers for chronic disease. Approximately one-third of United States (USA) children in this age group are overweight or obese. Therefore, attention to factors affecting dietary intake as one of the primary contributors to obesity is important. Early adolescents consume foods and beverages during eating occasions that occur with and without parental supervision. Parents may influence eating behaviors of early adolescents during eating occasions when they are present or during independent eating occasions by engaging in practices that affect availability of foods and beverages, and through perceived normative beliefs and expectations for intake. Therefore, the purpose of this article was to describe the influence of parenting practices on eating behaviors in general and when specifically applied to independent eating occasions of early adolescents. This information may be helpful to inform parenting interventions targeting obesity prevention among early adolescents focusing on independent eating occasions.

Eating under observation: a systematic review and meta-analysis of the effect that heightened awareness of observation has on laboratory measured energy intake

BACKGROUND

Laboratory paradigms are commonly used to study human energy intake. However, the extent to which participants believe their eating behavior is being measured may affect energy intake and is a methodologic factor that has received little consideration.

OBJECTIVE

Our main objective was to examine available evidence for the effect that heightened awareness of observation has on energy intake in a laboratory setting.

DESIGN

We systematically reviewed laboratory studies that allowed for experimental examination of the effect that heightened awareness of observation has on energy intake. From these experimental studies we combined effect estimates using inverse variance meta-analysis, calculating the standardized mean difference (SMD) in energy intake between heightened-awareness and control conditions and qualitatively synthesized potential moderators of this effect.

RESULTS

Nine studies, providing 22 comparisons, were eligible for inclusion. These studies largely sampled young women and examined the energy intake of energy-dense snack foods. Evidence indicated that heightened awareness of observation was associated with reduced energy intake when compared with the control condition (random-effects SMD: 0.45; 95% CI: 0.25, 0.66; P < 0.0001). We found little evidence that the type of experimental manipulation used to heighten awareness moderated the overall effect.

CONCLUSIONS

The available evidence to date suggests that heightened awareness of observation reduces energy intake in a laboratory setting. These findings suggest that laboratory studies should attempt to minimize the degree to which participants are aware that their eating behavior is being measured.

Making food labels social: The impact of colour of nutritional labels and injunctive norms on perceptions and choice of snack foods

Recent studies report that using green labels to denote healthier foods, and red to denote less healthy foods increases consumption of green- and decreases consumption of red-labelled foods. Other symbols (e.g. emoticons conveying normative approval and disapproval) could also be used to signal the healthiness and/or acceptability of consuming such products. The present study tested the combined effects of using emoticons and colours on labels amongst a nationally representative sample of the UK population (n = 955). In a 3 (emoticon expression: smiling vs. frowning vs. no emoticon) × 3 (colour label: green vs. red vs. white) ×2 (food option: chocolate bar vs. cereal bar) between-subjects experiment, participants rated the level of desirability, healthiness, tastiness, and calorific content of a snack bar they had been randomised to view. At the end they were further randomised to view one of nine possible combinations of colour and emoticon labels and asked to choose between a chocolate and a cereal bar. Regardless of label, participants rated the chocolate as tastier and more desirable when compared to the cereal bar, and the cereal bar as healthier than the chocolate bar. A series of interactions revealed that a frowning emoticon on a white background decreased perceptions of healthiness and tastiness of the cereal bar, but not the chocolate bar. In the explicit choice task selection was unaffected by label. Overall nutritional labels had limited effects on perceptions and no effects on choice of snack foods. Emoticon labels yielded stronger effects on perceptions of taste and healthiness of snacks than colour labels. Frowning emoticons may be more potent than smiling emoticons at influencing the perceived healthiness and tastiness of foods carrying health halos.

Social Norms Shift Behavioral and Neural Responses to Foods

Obesity contributes to 2.8 million deaths annually, making interventions to promote healthy eating critical. Although preliminary research suggests that social norms influence eating behavior, the underlying psychological and neural mechanisms of such conformity remain unexplored. We used fMRI to investigate whether group norms shift individuals' preferences for foods at both behavioral and neural levels. Hungry participants rated how much they wanted to eat a series of healthy and unhealthy foods and, after each trial, saw ratings that ostensibly represented their peers' preferences. This feedback was manipulated such that peers appeared to prefer each food more than, less than, or as much as participants themselves. After a delay, participants rerated each food. Participants' second ratings shifted to resemble group norms. Initial consensus, as compared to disagreement, with peers produced activity in the nucleus accumbens, a region associated with reward prediction errors. Furthermore, the strength of this activity predicted the extent to which participants' ratings conformed to peer ratings, suggesting that the value associated with consensus drives social influence. Ventromedial prefrontal cortex (vMPFC), a region associated with value computation, initially responded more strongly to unhealthy, as compared to healthy, foods. However, this effect was “overwritten” by group norms. After individuals learned their peers' preferences, vMPFC responses tracked the popularity, but not the healthfulness, of foods. Furthermore, changes in vMPFC activity tracked social influence over behavioral ratings. These data provide evidence that group norms can shift food preferences, supporting the use of norms-based interventions to promote healthy eating.

Dishware size and snack food intake in a between-subjects laboratory experiment

OBJECTIVE

The use of smaller dishware as a way of reducing food consumption has intuitive appeal and is recommended to the general public. Recent experimental studies have failed to find an effect of plate size on food intake, although the methods used across studies have varied. The aim of the present study was to examine the effect that bowl size had on snack food consumption in a 'typical' snacking context (snacking while watching television).

DESIGN

Between-subjects.

SETTING

Laboratory experiment.

SUBJECTS

Sixty-one adult participants served themselves and ate popcorn while watching television. Participants were randomly assigned to serve themselves with and eat from either a small or a large bowl.

RESULTS

The use of a smaller bowl size did not reduce food consumption. Unexpectedly, participants in the small bowl condition tended to consume more popcorn (34·0 g) than participants in the large bowl condition (24·9 g; 37 % increase, d=0·5), although the statistical significance of this difference depended on whether analyses were adjusted to account for participant characteristics (e.g. gender) associated with food intake (P=0·02) or not (P=0·07).

CONCLUSIONS

Counter to widely held belief, the use of a smaller bowl did not reduce snack food intake. Public health recommendations advising the use of smaller dishware to reduce food consumption are premature, as this strategy may not be effective.

Effects of Previous Fruit Intake, Descriptive Majority Norms, and Message Framing on Fruit Intake Intentions and Behaviors in Dutch Adults Across a 1-Week Period

OBJECTIVE

To test the effects of descriptive norm and message framing on fruit intake (intentions) in Dutch adults.

DESIGN

Randomized pretest-posttest study using a 2 × 2 design.

SETTING

Internet-based.

PARTICIPANTS

Dutch adults recruited via leaflets and announcements on intranet and Internet and who provided immediate intention (n = 294) and 1-week follow-up intention and fruit intake data (n = 177).

INTERVENTION

Messages combining information on intake of others (low vs high intake) with information about positive or negative outcomes of (in)sufficient fruit intake.

MAIN OUTCOME MEASURES

Fruit intake intentions and fruit intake.

ANALYSIS

Analyses of covariance.

RESULTS

Those already consuming sufficient fruit and receiving negative information about insufficient fruit intake increased their motivation to consume sufficient fruit immediately (P = .03), but not at 1-week follow-up. Those who read positive information about sufficient fruit intake reported higher fruit consumption than those who read negative information about insufficient fruit intake (P = .03). This was stronger in those already consuming sufficient fruit. There were no effects of descriptive norm information (P > .19).

CONCLUSIONS AND IMPLICATIONS

Information about outcomes was more persuasive than descriptive majority norm information. Effects were generally stronger in those already consuming sufficient fruit.

Personal and social norms for food portion sizes in lean and obese adults

Background

Portion size is an important component of dietary advice for weight control, but little is known about what portion sizes people consider “normal”. This study determined the effect of BMI, gender, dietary restraint, and liking of the food on personal and social portion size norms for a range of foods, and the degree of certainty over the norms.

Methods

30 lean (BMI 20-25kg/m²) and 30 obese (BMI 30-35kg/m²) men and women (aged 18-60years) viewed 17 different portion sizes of 12 foods on a computer screen on two occasions a week apart. Participants responded ‘more’ or ‘less’ to each photograph reflecting personal portion size preference or perceived portion sizes of others. Personal and social norms for portion sizes of each food were determined using the method of constant stimuli giving a sigmoidal curve of the probability of answering ‘less’ over a range of portion sizes. The slope of the sigmoid at the norm gave a measure of certainty about the norm. Regression models were used to examine the effect of BMI, gender, dietary restraint and liking of the food on personal norms, social norms, the relationship between norms, and the slopes.

Results

Personal norms were significantly larger in the obese (p=0.026), men (p<0.001), those with lower dietary restraint (p<0.001), and those with higher liking for the food (p<0.001). Social norms were larger for women (p=0.012). The slopes at the norms were 30% shallower in the obese and in men (p<0.001).

Conclusion

Larger personal norms for portion size among the obese, men, those with lower dietary restraint, and those with higher liking for a food imply greater consumption, which may undermine weight control. Shallower slopes for norms in the obese and in men may imply less clearly defined habitual portion sizes.

Drinking like everyone else: trait self-control moderates the association between peer and personal heavy episodic drinking

BACKGROUND

Alcohol consumption often appears to be under social influence. However, we know relatively little about whether some people are particularly likely to exhibit similar drinking patterns to their peers.

OBJECTIVES

Here we tested the extent to which trait social approval concerns and trait self-control are associated with the likelihood that individuals display similar heavy episodic drinking patterns to their peers.

METHOD

One thousand and fifty-six young adults participated in an online study. We measured trait social approval concerns (the Need to Belong scale) and trait self-control (the Self-Control scale) alongside personal heavy episodic drinking and perceptions of peer heavy episodic drinking.

RESULTS

Beliefs that one's peers (other students) drank heavily were associated with heavier personal episodic drinking. This relationship was moderated by trait self-control: The correlation between personal heavy episodic drinking and perceived peer drinking was much stronger in those with low self-control compared with those with high self-control. Contrary to hypotheses, trait social approval concerns did not moderate the relationship between perceived peer drinking and personal heavy episodic drinking.

CONCLUSIONS

Social norms about drinking could act as a form of informational cue for one's own alcohol consumption, but the extent to which individuals follow or override this cue may depend on individual differences in self-control.

Awareness of social influence on food intake. An analysis of two experimental studies

There is consistent evidence that the amount of food we consume can be influenced by the eating behaviour of other people. Some previous experimental studies reported that consumers are unaware of this influence on their behaviour. The present research tested whether people may be more aware of social influence on their eating than previously assumed. In two studies, participants (total n = 160) were exposed to information about the amount of snack food other people had been eating shortly before being served the same snack food and eating as much as they liked. After this, participants responded to questions regarding whether they thought their food intake had been socially influenced, and reported the reasons why they believed they had or had not been influenced. Of the 160 participants, 34% reported that they had been influenced, 10% were unsure and 56% reported they had not been influenced. Crucially, participants' reports of social influence appeared to be accurate; the food intake of participants reporting social influence was significantly affected by the amount of food other people had been eating, whereas the food intake of participants denying social influence was unaffected. Individuals may be more aware of the effect that social influence has on their eating behaviour than previously assumed. Further work is needed to identify the factors which determine whether people are susceptible to social influence on eating behaviour.

An integrative review of sleep for nutrition professionals

Sleep is an essential lifestyle factor that contributes to overall health. The inverse relation between sleep duration and weight status has revealed the importance of sleep in nutritional health. This integrative review builds foundational knowledge with regard to sleep vis-à-vis nutrition by summarizing the importance and process of sleep, current sleep recommendations and trends, as well as lifestyle contributors to poor sleep. Additionally, it details the association between sleep and obesity and potential mechanisms for this association. Furthermore, guidance is offered regarding the incorporation of sleep considerations in nutrition counseling, communication, and research. Like many other lifestyle factors that contribute to nutritional health, sleep needs to be considered when examining weight management and health promotion.