Evidence of a self-serving bias in people's attributions for their food intake.

People often fail to acknowledge external influences on their food intake, but there might be some circumstances in which people are willing to report that those external factors influenced their behavior. This study examined whether participants who believed that they had overeaten would indicate that the portion size they were served influenced their food intake. Participants (119 women) ate a pasta lunch at two separate sessions, one week apart. At the second session, participants were randomly assigned to receive either a regular portion of pasta (the same portion as the first session) or a large portion of pasta (a portion that was twice the size), and to receive false feedback about their food intake indicating that they had either eaten about the same as or substantially more than they had at the previous session. Participants were then asked to indicate the extent to which the amount of food served influenced how much they ate at that second session. Compared to participants who were informed that they had eaten the same amount across the two sessions, those who were informed that they ate more at the second session reported a stronger influence of the amount of food served if they also received a large portion of pasta, but not if they received a regular portion of pasta. These findings suggest that the willingness to implicate external influences (e.g., portion size) on one's food intake may be driven by a self-serving bias, providing an "excuse" for overeating. However, the external cue must be salient enough to be a plausible explanation for one's behavior.

Influence of social-normative information on the modeling of food-related decisions.

Social modeling is a powerful influence on people's food intake: When there is a clear and consistent norm, people eat more when eating with someone who eats a lot and eat less when eating with someone who eats only a little. In three studies, the present research examined how clear versus ambiguous social-normative information influences the modeling of food-related decisions. Using a novel online decision-making paradigm, female participants (total N = 1042) were provided with information about how many cookies previous participants had supposedly selected (no information was provided in the control condition), and then decided how many cookies they would choose for a snack. When there was a clear and consistent norm, the typical social modeling effect was observed. When there was a small number of "dissenters" whose responses conflicted with the norm set by the majority, participants' cookie selection still conformed to the behaviour of the majority (Studies 1 and 2). It was only when the behaviour of the previous participants was highly ambiguous that participants behaved as if they had been given no normative information (Study 3). By demonstrating that, except in extreme cases, people use the available information to discern a social norm that influences their behaviour, these findings highlight the power of social norms related to food-related decisions.

Food-based social comparisons influence liking and consumption.

This study examined the effects of food-based social comparisons on hedonic ratings and consumption of a meal. Participants were randomly assigned to one of three experimental conditions in which they were led to believe that they got a worse meal, a better meal, or the same meal as another participant. They then tasted and rated their own meal. Subsequent liking and ad lib food consumption were measured. Participants who were told that another person got a better meal than they did (upward comparison) liked their meal less than if they were told that another person received either the same meal as they did or a worse meal (downward comparison). Similarly, participants who were in the upward comparison condition ate less food than if they were in the control or downward comparison conditions. Consumption was mediated by liking. The results suggest that being told that someone else is eating a meal that is higher or lower in hedonic value than one's own meal induces hedonic contrast and influences liking and consumption.

What is restrained eating and how do we identify it?

Defining and measuring such qualities as restrained eating or dieting may require more than simply administering questionnaires and assuming that we are identifying the population that we wish to study. Different questionnaires may identify different types of restrained eaters, and even deciding what restrained eating consists of is a complicated endeavor. We discuss how to define and measure restrained eating, specifying key attributes, and acknowledging the problems inherent in relying on self-report instruments. We conclude that given the difficulties in defining such constructs as restrained eating, we need to specify more clearly exactly what our research questions are, in order to be sure that we are identifying the populations with the attributes necessary to answer those questions.

Modeling of food intake among restrained and unrestrained eaters.

The Theory of Normal Eating suggests that how much others eat sets an upper limit for how much it is appropriate to eat. This study tested the hypothesis that restrained eaters, who typically eat less than they want to, would be more responsive to a high-intake norm than would unrestrained eaters. Data were combined from 8 experimental studies (total N = 735 female participants; 305 restrained eaters, 430 unrestrained eaters). Each study: (a) included a low-intake norm, a high-intake norm, and a no-norm control condition; (b) measured participants' food intake; and (c) included the Restraint Scale as a measure of dietary restraint. There were no differences between restrained unrestrained eaters in the no-norm control condition or in the magnitude of the inhibition effect (i.e., the difference between the low-intake norm condition and the control condition). There was, however, a restraint difference in the magnitude of the augmentation effect (i.e., the difference between the high-intake norm condition and the control condition). Restrained eaters showed a larger augmentation effect (d = 0.58; 95% CI = 0.29, 0.87) than did unrestrained eaters (d = 0.20; 95% CI = -0.05, 0.45). Social norms provide an upper limit for acceptable food intake, with high-intake norms permitting (but not requiring) individuals to indulge themselves. The fact that restrained eaters were more responsive to the high-intake norm than were unrestrained eaters suggests that the high-intake norm gives restrained eaters permission to indulge when they typically eat less than they want to.

It's all in the timing: The effect of a healthy food cue on food choices from a pictorial menu.

The contemporary food-rich environment has been consistently linked to unhealthy eating. Emerging research suggests that changing the presentation context of unhealthy foods by introducing a subtle nudge in the form of a healthy food cue may promote healthier dietary choices. This study investigated the effect of the timing of a healthy food cue (before or simultaneously with food options) on food choices. Participants (n = 210) were presented with a pictorial café-style menu displaying a healthy food cue (basket of fruit and vegetables) either on the menu cover or inside the menu, or they received a control menu. Participants were asked to make one choice from each of three menu sections (meals, beverages, afters), and then completed a measure of dietary restraint. As predicted, participants chose a greater proportion of healthy food from the healthy-cue-before menu compared to both the healthy-cue-simultaneous and control menus. Furthermore, this effect was stronger for restrained eaters. The findings demonstrate that the timing of presentation of a healthy food cue is critical, and could be used to inform the design of menus in real-world environments, such as cafés and fast-food outlets, to promote healthier dietary choices.

Are there different types of dieters? A review of personality and dietary restraint.

We review the research on the association between personality and dietary restraint as measured by commonly-used self-report assessment instruments (Restraint Scale, TFEQ, DEBQ, and EDE-Q). In order to expand our understanding of the potentially different types of dieters, we examine the different personality profiles that emerge from existing studies of restraint and personality, including associations between restraint and body dissatisfaction and body focus, self-esteem, neuroticism, sensation seeking, impulsivity, perfectionism and narcissism. This research provides some preliminary evidence that different measures of restraint are associated not only with different eating behaviours, but that they capture different personality profiles.

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.

Hunger, taste, and normative cues in predictions about food intake.

Normative eating cues (portion size, social factors) have a powerful impact on people's food intake, but people often fail to acknowledge the influence of these cues, instead explaining their food intake in terms of internal (hunger) or sensory (taste) cues. This study examined whether the same biases apply when making predictions about how much food a person would eat. Participants (n = 364) read a series of vignettes describing an eating scenario and predicted how much food the target person would eat in each situation. Some scenarios consisted of a single eating cue (hunger, taste, or a normative cue) that would be expected to increase intake (e.g., high hunger) or decrease intake (e.g., a companion who eats very little). Other scenarios combined two cues that were in conflict with one another (e.g., high hunger + a companion who eats very little). In the cue-conflict scenarios involving an inhibitory internal/sensory cue (e.g., low hunger) with an augmenting normative cue (e.g., a companion who eats a lot), participants predicted a low level of food intake, suggesting a bias toward the internal/sensory cue. For scenarios involving an augmenting internal/sensory cue (e.g., high hunger) and an inhibitory normative cue (e.g., a companion who eats very little), participants predicted an intermediate level of food intake, suggesting that they were influenced by both the internal/sensory and normative cue. Overall, predictions about food intake tend to reflect a general bias toward internal/sensory cues, but also include normative cues when those cues are inhibitory. If people are systematically biased toward internal, sensory, and inhibitory cues, then they may underestimate how much food they or other people will eat in many situations, particularly when normative cues promoting eating are present.

The role of expectations in the effect of food cue exposure on intake.

Pre-exposure to food cues has often been shown to increase food intake, especially in restrained eaters. This study investigated the role of expectations in the effect of such pre-exposure on food intake. A sample of 88 undergraduate women was exposed to visual food cues (photos of grapes and chocolate-chip cookies). In a 2 × 2 × 2 design, participants were explicitly told to expect that they would be tasting and rating either grapes or chocolate-chip cookies. Participants subsequently completed an ostensible taste test, in which they tasted and rated either grapes or cookies, such that half were given the food that they had been led to expect and the other half were given the other food. Participants' restraint status (restrained versus unrestrained) was based on their scores on the Revised Restraint Scale (Herman & Polivy, 1980). A significant interaction between expected food and restraint status was found. When participants were led to expect that they would be tasting grapes, restrained and unrestrained eaters did not differ in their subsequent consumption (of either grapes or cookies). However, when participants were led to expect that they would be tasting cookies, restrained eaters ate significantly less (of both grapes and cookies) than did unrestrained eaters, even though craving ratings were similarly elevated for both restrained and unrestrained eaters. The findings are consistent with counteractive control theory in that restrained eaters who expected to eat a high caloric food may have been able to activate their dieting goal, thereby limiting their food intake. The findings further point to an important role for expectations in the understanding and regulation of food intake in restrained eaters.

"She got more than me". Social comparison and the social context of eating.

Eating is a social activity for most people. Other people influence what and how much an individual chooses and eats. Such social influence on eating has long been recognized and studied, but we contend here that one important social influence factor, social comparison, has been largely overlooked by researchers. We review the literature on comparing oneself to others on eating and weight-related dimensions, which appears to have an effect not only on eating per se, but also on self-image, body dissatisfaction, and emotions. Social comparison processes may well underlie many of the social influence findings discussed in this special issue.

Eating behavior, restraint status, and BMI of individuals high and low in perceived self-regulatory success.

The Perceived Self-Regulatory Success (PSRS) scale was developed to assess self-reported success at dieting and has been used to differentiate between successful and unsuccessful dieters (Fishbach, Friedman, & Kruglanski, 2003). We re-analyzed data from seventeen studies in order to examine whether PSRS predicted in-lab eating behavior of restrained and unrestrained eaters. We also explored the relation between body mass index, restraint, current dieting, and responding on the PSRS scale. It was found that successful dieters do not necessarily eat less than do unsuccessful dieters when a tempting food is available. Additionally, individuals who considered themselves to be successful dieters were more likely to be unrestrained eaters and current non-dieters than restrained eaters and current dieters. However, regardless of restraint status, individuals high in PSRS had lower BMI than those low in PSRS. These findings suggest that those who score high on the PSRS scale may not be concerned with regulating eating and weight. However, the restrained eaters who do score high on the PSRS scale appear to be successful at controlling their weight, despite not eating less in the lab.

The four undergraduate years. Changes in weight, eating attitudes, and depression.

Weight, eating attitudes, and depression were assessed in male and female students over the 4 years of university attendance, and the relation of weight changes to eating attitudes and depression was explored using self-report measures (Restraint Scale, EDI, CES-D) collected at six time points during the university years. Results showed that, in general, weight increased between year one and year four of university attendance for both men and women, with men gaining an average of 4.1 kg and women gaining an average of 3.2 kg. Weight gain was associated with increased body dissatisfaction and negative eating attitudes among women, whereas weight loss was associated with decreased negative eating attitudes. Well-being and eating attitudes of men who gained weight did not differ, either initially or at year four, from those of men who remained weight stable, whereas men who lost weight reported higher negative eating attitudes both initially and at year four. Weight gain, therefore, appears to be associated with negative outcomes, including greater preoccupation with eating and weight, for women, but not for men, while weight loss improves the attitudes only of women.

Getting a bigger slice of the pie. Effects on eating and emotion in restrained and unrestrained eaters.

Manipulated perceptions of the portion size of food influence subsequent eating by restrained and unrestrained eaters. In the present study, all participants were served a same-sized slice of pizza. For one-third of participants, their slice appeared larger than the slice being served to another ostensible participant, another third perceived their slice as smaller, and the final third did not see a second slice. All participants then proceeded to "taste and rate" cookies in an ad lib eating opportunity. A significant interaction reflected the fact that when the pizza slice was perceived as large, restrained eaters tended to eat more cookies whereas unrestrained eaters tended to eat less cookies. Emotion data suggest that the differential responses of restrained and unrestrained eaters to the belief that they have overeaten relative to another eater influenced their subsequent dissimilar ad lib eating behavior.

Inaccessible food cues affect stress and weight gain in calorically-restricted and ad lib fed rats.

Research suggests that caloric restriction (CR) is beneficial; however, the effects of CR in the context of food cues are unclear. A 2 (food cue vs. no cue)x2 (CR vs. ad lib) between-subjects design was employed to test these effects in 40 rats. It was predicted that cue exposure and CR would induce stress, and that these factors might interact synergistically. The results demonstrated that cue-exposed CR rats weighed less than did non-exposed CR rats. A blunted stress response was evident in CR rats relative to ad lib rats. Finally, cue-exposed rats had higher corticosterone levels and body weight during ad lib feeding than did non-cued rats. These results suggest that both CR and chronic food-cue exposure can be stressful, and the implications of this research are discussed in the context of humans' 'obesigenic' environment.

What does it mean to overeat?

"Overeating" is a significant public health concern, but little is known about how lay people conceptualize overeating. This study explored participants' conceptions of overeating. Participants were 175 university students and 296 community members (56% women) who were asked to rate the extent to which several statements reflected the concept of "overeating" (1 = Does not capture the meaning at all; 7 = Captures the meaning perfectly). Results showed that eating outside of hunger was viewed as being most strongly linked to the conceptualization of overeating; mindless eating, eating more than some normative amount, and a lack of restriction were all moderately linked to the conceptualization of overeating; and the quality of the food/eating style was rated as least relevant to the conceptualization of overeating. Participants with a higher BMI, participants who perceived themselves as fat, restrained eaters, and participants with an indication of eating pathology rated all of the constructs as more relevant to the concept of overeating than did their respective counterparts, but their overall pattern of responding was the same. The present research provides some initial insights into people's thoughts on what it means to "overeat," which is important given that simply believing that one has overeaten (regardless of the actual amount consumed) can have adverse psychological and behavioral consequences. These insights provide an avenue for future research to explore whether lay conceptions could be more adaptively reshaped to reduce the negative effects of perceived overeating.

Internal and external moderators of the effect of variety on food intake.

Many factors contribute to how much we eat. One such factor is the variety of different foods available. The current article reviews the variety literature with a specific focus on the factors that moderate the effects of variety on food intake and that moderate the processes that may underlie the variety effect (i.e., sensory-specific satiety and monotony). The moderators have been categorized as being of either an internal nature or an external nature. The literature suggests that internal moderators, including characteristics such as gender, weight, and dietary restraint, do not act as moderators of the variety effect. One possible exception to the absence of internal moderators is old age. Alternatively, external moderators, such as particular properties of food and the eater's perception of the situation, appear to affect the strength of the variety effect on intake to some degree. An evolutionary hypothesis may account for the distinct roles that internal and external variables play in moderating the variety effect. (PsycINFO Database Record (c) 2009 APA, all rights reserved).

Who gains or who loses weight? Psychosocial factors among first-year university students.

Self-reported weight changes over 7 months and their relation to psychosocial characteristics (self-esteem, depression, social support, perceived stress and transition perception) and eating attitudes and behaviors (restrained eating and Eating Disorder Inventory subscales [EDI]) were assessed in first-year male and female students at six Canadian universities (N=2753). Results showed small but significant weight increases over time in males and females (M=1.5 kg). Males who lost weight versus those who gained reported greater negative well-being and more negative feelings about university transition. Females who either lost or gained weight had higher initial restraint and EDI scores than did weight maintainers. At 3 months, total EDI and body dissatisfaction increased in female weight gainers compared to weight losers, plus greater drive for thinness compared to weight maintainers. Thus, males distressed at the transition from high school to university appear more likely to lose weight while well-adjusted males are more likely to gain weight. For females, however, weight gain is associated with more negative well-being and preoccupations with weight and eating.

Genetic and environmental influences on restrained eating behavior.

OBJECTIVE: We examined the relative contributions of genetic and environmental influences to restrained eating. METHOD: Restrained eating was assessed by the Restraint Scale in a survey mailed to all twins enrolled in the University of Washington Twin Registry. We used structural equation modeling to estimate genetic and nongenetic contributions to restrained eating. RESULTS: 1,196 monozygotic (MZ), 456 same-sex dizygotic (DZ) twins, and 447 opposite-sex twins were included in analyses. Restraint Scale scores were more closely correlated in MZ twins (r(male) = .55, r(female) = .55) than in same-sex DZ twins (r(male) = .31, r(female) = .19). Based on structural equation modeling, the estimated heritability for restrained eating, adjusted for body mass index (BMI) and sex, was 43% (95% confidence interval 35-50%). There was little evidence for common environmental effects. DISCUSSION: These results indicate an inherited component to restrained eating. Genes could influence restrained eating directly or through inherited mediators such as personality factors or tendencies to gain weight.