Sensory and social influences on ice cream consumption by males and females in a laboratory setting

Snack Package Size and Variety Differentially Influence Energy Intake and Food Choices in Healthy Adults

BACKGROUND

While energy and nutritional content of snacks can contribute to overconsumption, other factors within the modern food environment may also influence the amount and types of snacks consumed.

OBJECTIVES

The aim was to examine whether snack package size and variety influence free-living snacking behavior in healthy adults. The impact of intuitive eating score on snacking behavior was also examined.

METHODS

Thirty adults [age: 23.6 ± 0.8 y; BMI (kg/m2): 22.8 ± 0.5] participated in a randomized crossover-design study. Participants were provided, in randomized order, with the following isocaloric snack exposures to consume for 3 d/exposure-1) CONTROL: highly appealing/appetizing snacks (e.g., dessert snacks, candy, savory snacks, fruits and vegetables, protein snacks); 2) LARGE-PACKAGE: similar snacks as CONTROL but in larger package sizes; and 3) VARIETY: larger variety of snacks. The primary outcomes included the 3-d average ad libitum snack energy, macronutrient content, and food choices for each snack exposure. The secondary outcome was the intuitive eating score and snacking behavior.

RESULTS

LARGE-PACKAGE increased snack intake by 11.9% (1150 ± 81 kcal) compared with CONTROL (1030 ± 71 kcal, P = 0.04), whereas VARIETY snack intake (1030 ± 69 kcal) was no different from CONTROL (P = 1.0). LARGE-PACKAGE increased consumption of desserts compared with CONTROL (P = 0.03) and VARIETY (P = 0.02). Alternately, VARIETY increased consumption of fruits and vegetables compared with LARGE-PACKAGE (P = 0.01) and CONTROL (P = 0.01). Intuitive eating score was not significantly associated with snack intake or snack choice (all, P > 0.05).

CONCLUSIONS

Snack package size and variety differentially influence energy intake and food choices in healthy adults. This trial was registered atclinicaltrials.gov (NCT03940105).

Negative energy balance during military training: The role of contextual limitations

During multiday training exercises, soldiers almost systematically face a moderate-to-large energy deficit, affecting their body mass and composition and potentially their physical and cognitive performance. Such energy deficits are explained by their inability to increase their energy intake during these highly demanding periods. With the exception of certain scenarios in which rations are voluntarily undersized to maximize the constraints, the energy content of the rations are often sufficient to maintain a neutral energy balance, suggesting that other limitations are responsible for such voluntary and/or spontaneous underconsumption. In this review, the overall aim was to present an overview of the impact of military training on energy balance, a context that stands out by its summation of specific limitations that interfere with energy intake. We first explore the impact of military training on the various components of energy balance (intake and expenditure) and body mass loss. Then, the role of the dimensioning of the rations (total energy content above or below energy expenditure) on energy deficits are addressed. Finally, the potential limitations inherent to military training (training characteristics, food characteristics, timing and context of eating, and the soldiers' attitude) are discussed to identify potential strategies to spontaneously increase energy intake and thus limit the energy deficit.

Eating self-efficacy: validation of a new brief scale

PURPOSE

Eating self-efficacy (ESE) is the belief in one's ability to self-regulate eating. Social and emotional situations may be differently challenging depending on the individual eating habits, body mass index and affects. Several ESE scales have been developed but most of them focus on weight management, dieting or healthy eating. The aim of the study was to validate a new brief scale assessing ESE in situations in which people face social or emotional pressures for excessive food intake.

METHODS

Study 1: A sample of 412 volunteer females (age M = 25.44 ± 5.03) completed a first 25-item version of the scale. Exploratory factor analysis (EFA) was conducted for selecting a subgroup of items composing the ESE brief scale (ESEBS). Study 2 assessed its psychometric properties through a Confirmatory Factor Analysis (CFA), analyzing the responses of 410 volunteer adults (273 females, 137 males).

RESULTS

EFA of Study 1 evidenced a bifactorial structure. Four items for each factor were selected, explaining 63% of the variance. Study 2 confirmed the good fit of the bifactorial model (CFI = 0.9589; χ² (19) = 62.852, p < 0.001; RMSEA = 0.075; SRMR = 0.040) and provided support for the measurement invariance of the scale across gender. The internal consistency was as follows: Social (α = 0.786), Emotional (α = 0.820). The concurrent validity of the subscales was demonstrated by significant latent negative correlations with measures of eating disorders and emotional eating.

CONCLUSIONS

The 8-items ESEBS appears as a valid and reliable instrument to assess eating self-efficacy related to social and emotional situations. Future studies should evaluate its potential use in non-clinical and clinical research and interventions.

LEVEL OF EVIDENCE

Level V, descriptive cross-sectional study.

A new measurement tool to assess the deliberate overfeeding of others: The Feeder questionnaire

Whilst overeating is often influenced by others in an implicit way, people may also explicitly encourage others to overeat. This has been labelled being "a Feeder" but to date, this more deliberate trait remains neglected. This study aimed to conceptualize being "a Feeder" in terms of motivations and behaviour and to operationalize this construct with a new measurement tool through five stages with three discrete samples. Using the definition of a Feeder as "someone who offers others food even when they are not hungry" a preliminary qualitative study (n = 5) clarified the behaviour of a Feeder and revealed six motivations for such feeder behaviour. These six motivational dimensions and the feeder behaviours were operationalized with individual items and the psychometric properties of the scale were assessed using two independent samples (n = 116; n = 113). The final 27-item measure consisted of six motivational factors (affection; waste avoidance; status; hunger avoidance; offloading; manners) and one behaviour factor, all with good internal consistency (α ≥ .7). The two samples were then merged (n = 229) to describe motivations and behaviour and to assess the association between them. The best predictors of feeder behaviour were love, offloading, manners and status. This new Feeder questionnaire has a strong factor structure and good internal consistency and could be used for further research or clinical practice.

Mere presence of co-eater automatically shifts foraging tactics toward 'Fast and Easy' food in humans

Competition for food resources is widespread in nature. The foraging behaviour of social animals should thus be adapted to potential food competition. We conjectured that in the presence of co-foragers, animals would shift their tactics to forage more frequently for smaller food. Because smaller foods are more abundant in nature and allow faster consumption, such tactics should allow animals to consume food more securely against scrounging. We experimentally tested whether such a shift would be triggered automatically in human eating behaviour, even when there was no rivalry about food consumption. To prevent subjects from having rivalry, they were instructed to engage in a 'taste test' in a laboratory, alone or in pairs. Even though the other subject was merely present and there was no real competition for food, subjects in pairs immediately exhibited a systematic behavioural shift to reaching for smaller food amounts more frequently, which was clearly distinct from their reaching patterns both when eating alone and when simply weighing the same food without eating any. These patterns suggest that behavioural shifts in the presence of others may be built-in tactics in humans (and possibly in other gregarious animals as well) to adapt to potential food competition in social foraging.

A systematic review and meta-analysis of the social facilitation of eating

BACKGROUND

Research suggests that people tend to eat more when eating with other people, compared with when they eat alone, and this is known as the social facilitation of eating. However, little is known about when and why this phenomenon occurs.

OBJECTIVES

This review aimed to quantify the evidence for social facilitation of eating and identify moderating factors and underlying mechanisms.

METHODS

We systematically reviewed studies that used experimental and nonexperimental approaches to examine food intake/food choice as a function of the number of co-eaters. The following databases were searched during April 2019: PsychInfo, Embase, Medline, and Social Sciences Citation Index. Studies that used naturalistic techniques were narratively synthesized, and meta-analyses were conducted to synthesize results from experimental studies.

RESULTS

We reviewed 42 studies. We found strong evidence that people select and eat more when eating with friends, compared with when they eat alone [Z = 5.32; P < 0.001; standardized mean difference (SMD) = 0.76; 95% CI: 0.48, 1.03]. The meta-analysis revealed no evidence for social facilitation across studies that had examined food intake when participants ate alone or with strangers/acquaintances (Z = 1.32; P = 0.19; SMD = 0.21, 95% CI: -0.10, 0.51). There was some evidence that the social facilitation of eating is moderated by gender, weight status, and food type. However, this evidence was limited by a lack of experimental research examining the moderating effect of these factors on the social facilitation of eating among friends. In 2 studies, there was evidence that the effect of the social context on eating may be partly mediated by longer meal durations and the perceived appropriateness of eating.

CONCLUSIONS

Findings suggest that eating with others increases food intake relative to eating alone, and this is moderated by the familiarity of co-eaters. The review identifies potential mechanisms for the social facilitation of eating and highlights the need for further research to establish mediating factors. Finally, we propose a new theoretical framework in which we suggest that the social facilitation of eating has evolved as an efficient evolutionary adaptation.

Understanding the Relationship Between Food Variety, Food Intake, and Energy Balance

PURPOSE OF REVIEW

In accordance with US dietary guidance, incorporating variety into the diet can align with energy balance, though greater food variety in some categories may make energy balance more challenging. Thus, experimental and epidemiologic evidence is summarized on the relationship between food variety, food and energy intake, and energy balance.

RECENT FINDINGS

Lab-based, experimental research consistently demonstrates that greater variety within foods or sensory characteristics of food increases food and energy intake within an eating occasion. Epidemiologic evidence is less consistent, potentially driven by differing methodologies, particularly in defining and measuring food variety. Moreover, the effect of variety on energy balance appears to be moderated by food energy density. Integrating insights from experimental and epidemiologic research are essential for strengthening food variety guidance including developing evidence-based definitions of food variety, understanding moderators of the relationship, and developing practical guidance interpretable to consumers.

To Message or Browse? Exploring the Impact of Phone Use Patterns on Male Adolescents' Consumption of Palatable Snacks

Surveys of mobile phone usage suggest that adolescents habitually use their phones while eating. In this study, we explored whether the manner in which one uses a mobile phone – to engage in a social or non-social activity – can affect appetite regulation. Participants were fifty male adolescents randomly assigned to engage in one of the following phone-based activities: (1) sending and receiving messages (social activity), or (2) reading a neutral article (non-social activity). When given the opportunity to snack, participants in the messaging group consumed more snacks that those who read the article. Our findings correspond to a large literature emphasizing social influences on food intake, and suggest that phone use patterns may predispose an individual to overeating.

The social facilitation of eating or the facilitation of social eating?

People eat more when they eat in groups. Various explanations have been offered for this "social facilitation" of eating. We consider these explanations and find most of them wanting, especially insofar as they do not take into account the increased per capita provision of food when people eat together. We suggest that people often prefer to eat in groups precisely because it offers them an opportunity to overindulge.

The use of a wearable camera to capture and categorise the environmental and social context of self-identified eating episodes

Research investigating the influence of the environmental and social factors on eating behaviours in free-living settings is limited. This study investigates the utility of using wearable camera images to assess the context of eating episodes. Adult participants (N = 40) wore a SenseCam wearable camera for 4 days (including 1 familiarisation day) over a 15-day period in free-living conditions, and had their diet assessed using three image-assisted multiple-pass 24-hour dietary recalls. The images of participants' eating episodes were analysed and annotated according to their environmental and social contexts; including eating location, external environment (indoor/outdoor), physical position, social interaction, and viewing media screens. Data for 107 days were used, with a total of 742 eating episodes considered for annotation. Twenty nine per cent (214/742) of the episodes could not be categorised due to absent images (12%, n = 85), dark/blurry images (8%, n = 58), camera not worn (7%, n = 54) and for mixed reasons (2%, n = 17). Most eating episodes were at home (59%) and indoors (91%). Meals at food retailers were 24.8 minutes longer (95% CI: 13.4 to 36.2) and were higher in energy (mean difference = 1196 kJ 95% CI: 242, 2149) than at home. Most episodes were seated at tables (27%) or sofas (26%), but eating standing (19%) or at desks (18%) were common. Social interaction was evident for 45% of episodes and media screens were viewed during 55% of episodes. Meals at home watching television were 3.1 minutes longer (95% CI: -0.6 to 6.7) and higher in energy intake than when no screen was viewed (543 kJ 95% CI: -32 to 1120). The environmental and social context that surrounds eating and dietary behaviours can be assessed using wearable camera images.

The social facilitation of eating. A review

The social facilitation of eating (i.e., people eating more in groups than when alone) has been studied for about three decades now. In this paper, we review the empirical research (diary studies, observational studies, and experimental studies) of social facilitation, attending to factors that increase or decrease socially facilitated eating. We also review the various explanations (e.g., "time extension") that have been offered for the effect and offer our own speculations as to the underlying mechanisms. Further, we discuss promising directions for future research on the social facilitation of eating.

Dietary habits and behaviors associated with nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is one of the most frequent causes of health problems in Western (industrialized) countries. Moreover, the incidence of infantile NAFLD is increasing, with some of these patients progressing to nonalcoholic steatohepatitis. These trends depend on dietary habits and life-style. In particular, overeating and its associated obesity affect the development of NAFLD. Nutritional problems in patients with NAFLD include excess intake of energy, carbohydrates, and lipids, and shortages of polyunsaturated fatty acids, vitamins, and minerals. Although nutritional therapeutic approaches are required for prophylaxis and treatment of NAFLD, continuous nutrition therapy is difficult for many patients because of their dietary habits and lifestyle, and because the motivation for treatment differs among patients. Thus, it is necessary to assess the nutritional background and to identify nutritional problems in each patient with NAFLD. When assessing dietary habits, it is important to individually evaluate those that are consumed excessively or insufficiently, as well as inappropriate eating behaviors. Successful nutrition therapy requires patient education, based on assessments of individual nutrients, and continuing the treatment. In this article, we update knowledge about NAFLD, review the important aspects of nutritional assessment targeting treatment success, and present some concrete nutritional care plans which can be applied generally.

Peers and Obesity during Childhood and Adolescence: A Review of the Empirical Research on Peers, Eating, and Physical Activity

Obesity during childhood and adolescence is a growing problem in the United States, Canada, and around the world that leads to significant physical, psychological, and social impairment. In recent years, empirical research on factors that contribute to the development and maintenance of obesity has begun to consider peer experiences, such as peer rejection, peer victimization, and friendship. Peer experiences have been theoretically and empirically related to the “Big Two” contributors to the obesity epidemic, eating and physical activity, but there has not been a comprehensive review of the extant empirical literature. In this article, we review and synthesize the emerging theoretical and empirical literatures on peer experiences in relation to: (a) eating (food consumption and food selection); and (b) physical activity, during childhood and adolescence. A number of limitations and issues in the theoretical and empirical literatures are also discussed, along with future research directions. In conclusion, we argue that the involvement of children and adolescents’ peer networks in prevention and intervention efforts may be critical for promoting and maintaining positive behavioral health trajectories.

A review of visual cues associated with food on food acceptance and consumption

Several sensory cues affect food intake including appearance, taste, odor, texture, temperature, and flavor. Although taste is an important factor regulating food intake, in most cases, the first sensory contact with food is through the eyes. Few studies have examined the effects of the appearance of a food portion on food acceptance and consumption. The purpose of this review is to identify the various visual factors associated with food such as proximity, visibility, color, variety, portion size, height, shape, number, volume, and the surface area and their effects on food acceptance and consumption. We suggest some ways that visual cues can be used to increase fruit and vegetable intake in children and decrease excessive food intake in adults. In addition, we discuss the need for future studies that can further establish the relationship between several unexplored visual dimensions of food (specifically shape, number, size, and surface area) and food intake.

Dietary (sensory) variety and energy balance

The prevalence of overweight and obesity in US adults is currently 68%, compared with about 47% in the early 1970s. Many dietary factors have been proposed to contribute to the US obesity epidemic, including the percentage of energy intake from fat, carbohydrate and protein; glycemic index; fruit and vegetable intake; caloric beverage intake; and fast food or other restaurant food intake. One factor that may also be important is the variety of foods in the diet having different sensory properties, that is, flavors, textures, shapes and colors. A host of studies show that when presented with a greater variety of foods within a meal, humans consume about 22% more energy compared to when only one food is available. These data are supported by laboratory animal studies on the effects of sensory variety on consumption as well as body weight and fat gain. Longer term experimental trials in humans lasting 1-2wk had mixed results but generally showed an increase in intake of 50-60kcal/d per additional food offered, provided at least 5 different foods per day were available. In only two studies to date has reducing dietary variety been explored as a potential method for weight loss. In those studies, which also incorporated a standard behavioral weight loss approach, there was no difference in weight loss when either snack food variety or low nutrient dense, high energy dense variety was limited. However, a broader treatment approach may be more effective, for example limiting the excess variety of foods high in energy density yet which provide little benefit to vitamin and mineral intake at each meal, and further studies are needed in this area.

Influence of peers and friends on children's and adolescents' eating and activity behaviors

Obesity during childhood and adolescence is a growing problem in the United States, Canada, and around the world that leads to significant physical, psychological, and social consequences. Peer experiences have been theoretically and empirically related to the "Big Two" contributors to the obesity epidemic, unhealthy eating and physical inactivity. In this article, we synthesize the empirical literature on the influence of peers and friends on youth's eating and physical activity. Limitations and issues in the theoretical and empirical literatures are also discussed, along with future research directions. In conclusion, we argue that the involvement of children's and adolescents' peer networks in prevention and intervention efforts may be critical for promoting and maintaining positive behavioral health trajectories. However, further theoretical and empirical work is needed to better understand the specific mechanisms underlying the effects of peers on youth's eating and physical activity.

Perceptions of undereaters: a matter of perspective?

We assume that people, to convey positive impressions of themselves, use the amounts eaten by others as limits beyond which their eating may be deemed excessive. One should, therefore, prefer eating partners who eat a lot because others' large intake renders one's own eating nonexcessive. Two studies were conducted to test this hypothesis. As predicted, participants liked confederates who ate more than they did better than those who ate less than they did, and they also rated their own intake as more appropriate when it had been exceeded by confederates than they did when it had been undercut by confederates. Noneating observers, instead, did not display a preference for eaters who ate more. Both noneating observers and active participants, however, rated eaters who ate less more positively than eaters who ate more on self-control-related items. We conclude that the nature of the behavior-impression association depends critically on the perspective of the rater.

Dietary variety impairs habituation in children

OBJECTIVE

The purpose of these studies was to test the hypothesis that dietary variety decreases the rate of habituation and increases energy intake in children.

DESIGN

In Experiment 1, salivation in response to the same or a variety of food cues was measured followed by consumption of the study food(s). In Experiment 2, children responded in a computer task to earn points for the same or a variety of low or high energy density foods, which were then consumed.

MAIN OUTCOME MEASURES

Salivation, number of responses, and energy intake were measured.

RESULTS

Participants in the same groups habituated faster than those in the variety groups (p = .05), and in Experiment 2, the effect of variety was independent of energy density. Participants in the variety groups also consumed more energy than those in the same groups in both experiments (p = .05).

CONCLUSIONS

Dietary variety disrupted habituation and increased energy intake in children. In addition, the response to dietary variety was independent of energy density, suggesting that increasing variety of low energy density foods may increase consumption.

Eating in larger groups increases food consumption

OBJECTIVE

To determine whether children's food consumption is increased by the size of the group of children in which they are eating.

DESIGN

Crossover study.

SETTING

University based preschool.

PARTICIPANTS

54 children, aged 2.5-6.5 years.

INTERVENTIONS

Each child ate a standardised snack in a group of three children, and in a group of nine children.

MAIN OUTCOME MEASURES

Amount each individual child consumed, in grams.

RESULTS

Amount eaten and snack duration were correlated (r = 0.71). The association between group size and amount eaten differed in the short (<11.4 min) versus the long (> or =11.4 min) snacks (p = 0.02 for the interaction between group size and snack duration). During short snacks, there was no effect of group size on amount eaten (16.7 (SD 11) g eaten in small groups vs 15.1 (6.6) g eaten in large groups, p = 0.42). During long snacks, large group size increased the amount eaten (34.5 (16) vs 26.5 (13.8), p = 0.02). The group size effect was partially explained by a shorter latency to begin eating, a faster eating rate and reduced social interaction in larger groups.

CONCLUSIONS

Children consumed 30% more food when eating in a group of nine children than when eating in a group of three children during longer snacks. Social facilitation of food consumption operates in preschool-aged children. The group size effect merits consideration in creating eating behaviour interventions.

Influence of physiological and subjective arousal on food intake in humans

OBJECTIVES

This study explored the influence of physiologic and subjective arousal on ambient factors of the food environment, such as the eating location, the presence of other people, sound, and time of day and on food intake. It was hypothesized that the influence of environmental stimuli on food intake would be mediated by arousal.

METHODS

College students were asked to wear heart rate monitors and to record their food intake in a 7-d diet diary. Subjective arousal (elation and excitement) and aspects of the eating environment were recorded for each meal occasion.

RESULTS

Results showed that subjective arousal seems to be related to food intake (P < 0.01) and appears to be affected by environmental stimuli such as the eating location (P < 0.01) and the number of people present (P < 0.01), but only small effects of some environmental stimuli on heart rate were found with higher average heart rates in restaurants (P < 0.05). No effects of heart rate on food intake were detected. Regression analyses failed to show arousal as a significant mediator between environmental stimuli and food intake.

CONCLUSION

It can be concluded that, for normal individuals in their everyday environment, ambient influences on food intake are not mediated by changes in arousal. However, the environment and the emotional state of the individual appear to play a role in the individual's eating behavior.

Meal duration mediates the effect of "social facilitation" on eating in humans

This experiment examined the 'time extension' explanation for the social facilitation effect, which is that people eat more as the number of co-eaters increases. Seventy male and 62 female participants ate a lunch consisting of pizza, cookies, and bottled water, alone or in (same-gender) groups of two or four and were given either 12 or 36 min in which to do so. The independent variables were gender, group size, and meal duration. The main dependent variable was amount consumed in the meal. The results showed that male participants ate more than did females, and participants eating the longer meal ate more than did those eating the shorter meal. However, the effect of group size was not significant. It was also the case that the amounts consumed by participants eating in two-person groups resembled one another to a greater extent than did of pairs of participants who ate alone or by participants in four-person groups. It was concluded that the results of the present paper provide strong support for the idea that the effect of group size on intake seen in previous studies is mediated by meal duration.

The office candy dish: proximity's influence on estimated and actual consumption

OBJECTIVE AND PURPOSE

Although there is increasing interest in how environmental factors influence food intake, there are mixed results and misunderstandings of how proximity and visibility influence consumption volume and contribute to obesity. The objective of this paper is to examine two questions: first, how does the proximity and salience of a food influence consumption volume? Second, are proximate foods consumed more frequently because they are proximate, or are they consumed more frequently because people lose track of how much they eat?

RESEARCH METHODS AND PROCEDURES

The 4-week study involved the chocolate candy consumption of 40 adult secretaries. The study utilized a 2 x 2 within-subject design where candy proximity was crossed with visibility. Proximity was manipulated by placing the chocolates on the desk of the participant or 2 m from the desk. Visibility was manipulated by placing the chocolates in covered bowls that were either clear or opaque. Chocolates were replenished each evening, and placement conditions were rotated every Monday. Daily consumption was noted and follow-up questionnaires were distributed and analyzed.

RESULTS

There were main effects for both proximity and visibility. People ate an average of 2.2 more candies each day when they were visible, and 1.8 candies more when they were proximately placed on their desk vs 2 m away. It is important to note, however, that there was a significant tendency for participants to consistently underestimate their daily consumption of proximately placed candies (-0.9) and overestimate their daily consumption of less proximately placed candies (+0.5).

DISCUSSION

These results show that the proximity and visibility of a food can consistently increase an adult's consumption of it. In addition, these results suggest that people may be biased to overestimate the consumption of foods that are less proximate, and to underestimate those that are more proximate. Knowing about these deviation tendencies is important for those attempting effectively monitor their consumption of fat and sugar.

Effect of ambience on food intake and food choice

Eating takes place in a context of environmental stimuli known as ambience. Various external factors such as social and physical surroundings, including the presence of other people and sound, temperature, smell, color, time, and distraction affect food intake and food choice. Food variables such as the temperature, smell, and color of the food also influence food intake and choice differently. However, the influence of ambience on nutritional health is not fully understood. This review summarizes the research on ambient influences on food intake and food choice. The literature suggests that there are major influences of ambience on eating behavior and that the magnitude of the effect of ambience may be underestimated. Changes in intake can be detected with different levels of the number of people present, food accessibility, eating locations, food color, ambient temperatures and lighting, and temperature of foods, smell of food, time of consumption, and ambient sounds. It is suggested that the manipulation of these ambient factors as a whole or individually may be used therapeutically to alter food intake and that more attention needs to be paid to ambience in nutrition-related research.

ENVIRONMENTAL FACTORS THAT INCREASE THE FOOD INTAKE AND CONSUMPTION VOLUME OF UNKNOWING CONSUMERS

Package size, plate shape, lighting, socializing, and variety are only a few of the environmental factors that can influence the consumption volume of food far more than most people realize. Although such environmental factors appear unrelated, they generally influence consumption volume by inhibiting consumption monitoring and by suggesting alternative consumption norms. For researchers, this review suggests that redirecting the focus of investigations to the psychological mechanisms behind consumption will raise the profile and impact of research. For health professionals, this review underscores how small structural changes in personal environments can reduce the unknowing overconsumption of food.

Effects of social interaction, physical environment and food choice freedom on consumption in a meal-testing environment

Consumption of pizza, salad and iced tea was assessed in four separate tests at a central location. Three aspects of context were added in successive tests-social interaction during consumption, the physical environment in which the food was consumed and choice among foods-so that the fourth test had all effects present. The proportion consumed averaged from 79 to 82% of the food presented and increased significantly in the presence of one or more of the context manipulations. Salad consumption was higher when there was a choice of dressings in an enhanced environment. Pizza and tea consumption were higher in an enhanced restaurant-like environment. Social interaction alone has no detectable impact on food consumption. It is concluded that people eat more in enhanced contexts and careful consideration should be given to the environment in studies of food consumption.

Effect of sensory perception of foods on appetite and food intake: a review of studies on humans

OBJECTIVE

How much do the sensory properties of food influence the way people select their food and how much they eat? The objective of this paper is to review results from studies investigating the link between the sensory perception of food and human appetite regulation.

CONTENT OF THE REVIEW

The influence of palatability on appetite and food intake in humans has been investigated in several studies. All reviewed studies have shown increased intake as palatability increased, whereas assessments of the effect of palatability using measures of subjective appetite sensations have shown diverging results, for example, subjects either feel more hungry and less full after a palatable meal compared to a less palatable meal, or they feel the opposite, or there is no difference. Whether palatability has an effect on appetite in the period following consumption of a test meal is unclear. Several studies have investigated which sensory properties of food are involved in sensory-specific satiety. Taste, smell, texture and appearance-specific satieties have been identified, whereas studies on the role of macronutrients and the energy content of the food in sensory-specific satiety have given equivocal results. Different studies have shown that macronutrients and energy content play a role in sensory-specific satiety or that macronutrients and energy content are not a factor in sensory-specific satiety. Sensory-specific satiety may have an important influence on the amount of food eaten. Studies have shown that increasing the food variety can increase food and energy intake and in the short to medium term alter energy balance. Further knowledge about the importance of flavour in appetite regulation is needed, for example, which flavour combinations improve satiety most, the possible connection between flavour intensity and satiety, the effect of persistence of chemesthetic sensation on palatability and satiety, and to what extent genetic variation in taste sensitivity and perception influences dietary habits and weight control.

Effects of the Presence of Others on Food Intake: A Normative Interpretation

The authors review the effect of the presence of others on food intake. In social facilitation studies, people tend to eat more in groups than when alone. In modeling studies, the presence of others may facilitate or inhibit intake, depending on how much these other people eat. Studies of impression management demonstrate that people tend to eat less in the presence of others than when alone. The authors attempt to reconcile these divergent literatures by reference to a model of inhibitory norms that govern eating. In the presence of palatable food, and in the absence of clear signals of satiety, people look outward to cues from the environment to determine when to stop eating. Socially derived inhibitory norms can account for either increased or decreased intake in the presence of others, depending on how much the others eat and the extent to which one is eager to impress them.

Biobehavioral influences on energy intake and adult weight gain

U.S. adults are now gaining more weight and becoming obese at an earlier age than in previous years. The specific causes of adult weight gain are unknown, but may be attributed to a combination of factors leading to positive energy balance. U.S. food supply data indicate that Americans have had a gradual increase in energy intake since 1970, and that per capita energy intake was 1.42 MJ/d (340 kcal/d) higher in 1994 than that in 1984. In contrast, self-reported physical activity remained constant between 1990 and 1998. Taken together, these data indicate that the increasing trend in U.S. adult weight gain is primarily attributable to overconsumption of energy. Epidemiological and experimental studies in animals and humans provide strong evidence that biobehavioral factors such as dietary variety, liquid (vs. solid) energy, portion size, palatability (taste), snacking patterns, restaurant and other away-from-home food, and dietary restraint and disinhibition influence hunger, satiety and/or voluntary energy intake. When these eating behaviors are consistently experienced either separately or in combination over the long term, they are likely to facilitate overeating. We provide a brief overview of the evidence to date for the role of these biobehavioral factors in contributing to excess energy intake and increases in body weight over time.

Memory for recent eating and its influence on subsequent food intake

The effect of being reminded of a recent eating episode on subsequent food intake was examined in unrestrained eaters. In Experiment 1, female participants were exposed to a "lunch cue" (in which they were asked to think about what they had eaten for lunch), or "no cue" (free thought condition), for 5 min prior to eating. Participants ate less following exposure to the "lunch cue" than the "no cue" condition. In Experiment 2, food intake was measured following exposure to either a "lunch today" cue, "lunch yesterday" cue or "no cue" condition. Intake in the "lunch today" condition was suppressed relative to both the "lunch yesterday" and "no cue" condition. Subjective ratings of hunger, fullness, and desire to eat did not vary as a function of cue type in either Experiment 1 or Experiment 2. These results are consistent with the suggestion that memory of recent eating is an important cognitive factor influencing food intake.

Dietary variety, energy regulation, and obesity

Increased variety in the food supply may contribute to the development and maintenance of obesity. Thirty-nine studies examining dietary variety, energy intake, and body composition are reviewed. Animal and human studies show that food consumption increases when there is more variety in a meal or diet and that greater dietary variety is associated with increased body weight and fat. A hypothesized mechanism for these findings is sensory-specific satiety, a phenomenon demonstrating greater reductions in hedonic ratings or intake of foods consumed compared with foods not consumed. Nineteen studies documenting change in preference, intake, and hedonic ratings of food after a food has been eaten to satiation in animals and humans are reviewed, and the theory of sensory-specific satiety is examined. The review concludes with the relevance of oral habituation theory as a unifying construct for the effects of variety and sensory-specific satiety, clinical implications of dietary variety and sensory-specific satiety on energy regulation, and suggestions for future research.

Self-presentational conflict in social eating situations: a normative perspective

This study explored the degree to which people adhere to norms for "appropriate" eating behavior in social situations. Of particular interest was how people determine what is appropriate behavior when they are faced with conflicting norms within a given situation. Participants tasted cookies while alone or while observed by the experimenter. Furthermore, participants were assigned to either a "no norm" condition in which they were given no indication of how much other people in the study had eaten, an "inhibition norm" condition in which they were led to believe that others had eaten minimally, or an "augmentation norm" condition in which they were led to believe that others in the study had eaten a lot. When they were alone, participants were influenced by the norms; but when they were observed, they ate minimally, regardless of the norms to which they were exposed. It seems that a norm for minimal eating superseded a matching norm which prescribes that people should use the intake of their peers as a guide for appropriate behavior. Implications of these findings and limitations of the study were discussed.

Criticisms of the satiety hypothesis as an explanation for within-session decreases in responding

The authors of four papers recently reported that satiation provides a better explanation than habituation for within-session decreases in conditioned responding. Several arguments question this conclusion. First, the contribution of habituation to within-session changes in responding seems clearly established. Information that is consistent with habituation, but that is difficult to reconcile with satiation, is not adequately addressed. Second, the limited evidence offered in support of satiation is ambiguous because the results are just as compatible with habituation as with other satiety variables. Finally, the term satiation is used in an intuitive way that is sometimes contradicted by research about the termination of ingestion. Use of the technical term satiation in a way that differs from its conventional usage will only isolate operant psychology from other areas of psychological research.

Socio-cultural determinants of meal size and frequency

Total energy intake and the frequency and size of meals are profoundly influenced by the socio-cultural context in which it occurs. Simply eating with one other person increases the average amount ingested in meals by 44% and with more people present the average meal size grows even larger. The impact of social facilitation of energy intake on the individual appears to result from genetic effects both on the individuals' sensitivity to the presence of other people and also on the number of other people an individual tends to eat with. Culture markedly affects the choice of foods in the diet and the pattern of meals over the day. However, many of the social, psychological and physical variables that influence intake are similar across cultures.

Social facilitation of food intake is mediated by meal duration

The effect of the number of others present on the amount of food eaten was investigated in the Netherlands by studying spontaneous meal size in 50 free-living young males and females. Subjects recorded food consumption, number of others present, hunger, taste of the food, food availability, and atmosphere at each eating or drinking moment for four (n = 30) or seven consecutive days (n = 20). The results of the study with four and the study with seven recording days were comparable. The mean Pearson within-person correlation coefficient between the number of other present and meal size was 0.24 (n = 50, p < 0.05). This correlation was significant for breakfast (0.40, p < 0.05) and snacks (0.18, p < 0.05), but not for lunch (r = 0.19, p > 0.05) and dinner (r = 0.15, p > 0.05). A path analysis showed no direct effect of the number of others on meal size, but revealed that social facilitation of spontaneous meal size was mediated by meal duration.