外文心理学文献2

obesity | VOLUME 19 NUMBER 10 | OCTOBER 2011 1957 nature publishing group articles Behavior and Psychology IntroductIon More than two-thirds of Americans over the age of 20 are now overweight and over one-third are obese (1). Yet, despite the fact that the majority of Americans are now overweight, a sub- stantial body of literature has documented weight bias among health-care professionals, teachers, potential employers, family members of obese individuals, and the media (2–7). In fact, the prevalence of perceived weight discrimination has increased by 66% since 1995 (8), and is now on par with rates of racial discrimination, especially toward obese women, who are tar- geted most frequently (9). Driving such discrimination and bias are the stereotypes that depict overweight individuals as sloppy, lazy, unmotivated, and less competent, and posit that overweight individuals are solely to blame for their weight status (4). The media is a particularly powerful source of both weight-based stereotypes and negative portrayals of obese individuals. In fact, overweight individuals remain among the last acceptable targets of derogatory humor in both television and film (2). When compared to thin tel- evision characters, overweight characters are more likely to be the targets of ridicule and humor, are commonly seen engag- ing in stereotypical eating behaviors, and are rarely depicted in romantic relationships (5,10). Weight bias in the media is not subtle, and instances of derogatory weight-based humor in television and film can be both verbal and direct (6). For exam- ple, a study of 18 popular prime-time television shows revealed a strong positive correlation between a female character’s weight and the frequency of derisive comments made toward her by others (11). Audience laughter was also positively cor- related with the character’s weight, and laughter (both live and canned) was highest when negative comments were directed to the overweight female characters. Taken together, these findings demonstrate both the prev- alence of weight bias in the media and its social acceptabil- ity. According to the latest Nielsen census data, the average American now watches over 150 h of television in a given month. The pervasiveness of weight bias coupled with such high rates of television viewing implies that the public is exposed to significant weight bias. Weight stigma is responsible for a range of negative psy- chological consequences for those who are targeted. Research demonstrates that individuals who have experienced weight- based stigmatization have increased risk of depression, low self-esteem, anxiety, poor body image, suicidality, and disor- dered eating (2,4,12). Importantly, many of these studies con- trol for BMI, indicating that it is the stigmatizing experience The Impact of Weight Stigma on Caloric Consumption Natasha A. Schvey1, Rebecca M. Puhl2 and Kelly D. Brownell1,2 The present study assessed the influence of exposure to weight stigma on energy intake in both overweight and normal-weight adult women. Seventy-three women (mean age: 31.71 ± 12.72 years), both overweight (n = 34) and normal weight (n = 39), were randomly assigned to view one of two videos depicting either weight stigmatizing material or neutral material, after which they consumed snacks ad libitum. Pre- and post-video measures included blood pressure, attitudes toward overweight individuals, and positive and negative affect. Participants’ body weight was measured, as was the number of kilocalories consumed following video exposure. Overweight women who watched the stigmatizing video ate more than three times as many kilocalories as overweight women who watched the neutral video (302.82 vs. 89.00 kcal), and significantly more calories than the normal-weight individuals who watched either the stigmatizing or the neutral video. A two-by-two analysis of covariance revealed that even after adjusting for relevant covariates, there was a significant interaction between video type and weight status in that when overweight, individuals consumed significantly more calories if they were in the stigmatizing condition vs. the neutral condition (F(1,65) = 4.37, P = 0.04, η 2 = 0.03). These findings suggest that among overweight women, exposure to weight stigmatizing material may lead to increased caloric consumption. This directly challenges the notion that pressure to lose weight in the form of weight stigma will have a positive, motivating effect on overweight individuals. Obesity (2011) 19, 1957–1962. doi:10.1038/oby.2011.204 1Department of Psychology, Yale University, New Haven, Connecticut, USA; 2Rudd Center for Food Policy and Obesity, Yale University, New Haven, Connecticut, USA. Correspondence: Natasha A. Schvey (natasha.schvey@yale.edu) Received 13 November 2010; accepted 5 June 2011; published online 14 July 2011. doi:10.1038/oby.2011.204 1958 VOLUME 19 NUMBER 10 | OCTOBER 2011 | www.obesityjournal.org articles Behavior and Psychology itself, rather than body weight, that is contributing to adverse psychological outcomes. A number of studies have also demonstrated that weight stigma is associated with unhealthy eating behaviors, such as eating in secret, refusing to diet, loss of control during eating, and binge-eating (12–14) as well as lower motivation to exercise and avoidance of physical activity (15,16), even after control- ling for variables such as BMI and body dissatisfaction. Some research suggests that individuals who internalize weight bias and negative stereotypes are more likely to engage in binge- eating and are more likely to report coping with stigma by refusing to diet and consuming more food (17). Thus, weight stigma may augment eating pathology and overeating, and at the same time, attenuate the desire to exercise. Furthermore, a recent study demonstrated that weight stigmatization was associated with greater caloric intake, higher program attri- tion, lower energy expenditure, less exercise, and less weight loss in a sample of treatment-seeking adults participating in a behavioral weight loss program (18). Thus, it appears that weight stigmatization may increase unhealthy behaviors that contribute to obesity. Despite increasing evidence linking weight bias to overeat- ing, to our knowledge, no studies have explored this link using actual food intake data. Since questionnaire methods are oftentimes nonconcordant with actual behavior, and under- reporting of energy intake is common (19), it is beneficial to examine the effect of weight stigma on actual, rather than reported intake. Therefore, the specific aims of this study were to determine whether exposure to a stigmatizing video (vs. a neutral video) influenced caloric consumption, mood, and blood pressure among both overweight and normal-weight women. We hypothesized that overweight women exposed to the stigmatizing video would consume the greatest number of kil- ocalories, have elevated blood pressure and endorse increased negative affect and fat phobia following the video, when com- pared to the other groups. Methods and Procedures Participants Overweight and normal-weight women were recruited for the study from a university and the surrounding community (city population: 124,000). The study was advertised as research exploring “the effects of video clips on mood, blood pressure, and other health indices.” Participants were recruited via flyers and online advertisements (e.g., craigslist.com) targeting both overweight and normal-weight women. To meet inclusion criteria, participants were required to be female, at least 18 years of age and have no medical complications that might affect energy consumption (e.g., pregnancy). In total, 102 individu- als contacted the researchers about participating. Participants were excluded for the following reasons: Male (N = 4), did not attend sched- uled appointment (N = 12), declined participation upon hearing study description or because of scheduling conflicts (N = 9), medical reasons (N = 3), and reported a 24-h fast before study initiation (N = 1). The final sample consisted of 73 women. This study focused exclusively on women as previous research has demonstrated that women may be more vulnerable to weight stigma than men (3,9) and women tend to report eating in response to negative affect more frequently than men (20,21). Procedure Participants were admitted individually to the laboratory between the hours of 2:30 and 4:30 pm, and were asked to refrain from eating 3 h before study initiation. Participants were told this was to ensure accu- racy of blood pressure measurement; however, the true purpose was to standardize hunger among participants. Following informed consent, participants were randomized to either the stigmatizing video or the neutral video condition, both of which were 10 min long. This created four study groups: Group 1: Overweight participants who viewed the stigmatizing video (Overweight/Stigma, n = 17), group 2: Normal- weight individuals who watched the stigmatizing video (Normal Weight/Stigma, n = 20), group 3: Overweight individuals who viewed the neutral video (Overweight/Neutral, n = 17), and group 4: Normal weight individuals who watched the neutral video (Normal Weight/ Neutral, n = 19). The stigmatizing video consisted of brief clips from popular television and movies that depict overweight and obese women and evoke negative weight-based stereotypes (e.g., clumsy, loud, and lazy). The types of scenes depicted in the video include teasing in the workplace, pratfalls involving obese individuals, and interpersonal instances of weight bias, and reflect some of the most common weight- based stereotypes that have been reported in the literature (2,4,22). The video had been pretested in a prior study investigating the effects of stigmatizing material on antifat attitudes in women (21). The control video consisted of a series of clips depicting neutral scenes (e.g., insur- ance commercials) and had similarly been pretested. Following randomization, participants’ blood pressure was meas- ured and questionnaires assessing demographics, positive and negative affect, “fat phobia,” depression, susceptibility to hunger, disinhibition, and restraint were administered. Prior research examining racial stigmatiza- tion has documented an increase in blood pressure following exposure to discriminatory material (23). Thus, blood pressure was assessed to detect possible physiological changes following the exposure to stigma- tizing stimuli. Participants then watched the video. Following the video, blood pres- sure was measured again. Participants were then given a second set of questionnaires and provided with three bowls of calorie-dense snack foods, which they were invited to consume freely. The snacks were 300 g of plain M&Ms, 300 g of Jelly Belly Jellybeans, and 86 g of SunChips. These foods were chosen because they are all highly palatable and contribute three diverse tastes. Participants were told that the snacks were provided because they had come in to the laboratory fasting. Participants were then left alone in the room to complete the post-video questionnaires and eat the snacks ad libitum. At the study conclusion, participants’ height and weight was measured and they were debriefed and compensated. The snack bowls were then weighed and number of grams consumed was recorded and converted into kilocalories. This study was approved by the Yale University Human Subjects Committee and all procedures were in accordance with its ethical standards. Measures A Medical condition phone screen was administered to exclude partici- pants with conditions that may affect energy intake. A Demographic Information Questionnaire assessed age, race, and ethnicity, educational background, and occupation. Total caloric intake was calculated based on the nutrition information on the packaging of the three snack foods. A food scale was used to weigh the snacks (300 g of M&M’s, 300 g of JellyBelly Jellybeans, and 86 g of SunChips) both before and after the participants were allowed access to them. Total number of kilocalories consumed was calculated. The Three-Factor Eating Questionnaire (TFEQ) (24,25) is a 51-item self-report questionnaire that assesses restraint, disinhibition, and sus- ceptibility to hunger. The restraint subscale is calculated from 21 items and assesses both cognitive and behavioral dietary restriction. The dis- inhibition subscale is derived from 16 items and measures the tendency to overeat, and the susceptibility to hunger subscale is derived from 14 items. Scores ≥14 represent the clinical range for restraint, scores ≥12 indicate the clinical range for disinhibition, and scores ≥11 signify a obesity | VOLUME 19 NUMBER 10 | OCTOBER 2011 1959 articles Behavior and Psychology clinical range of susceptibility to hunger (24). The TFEQ has been shown to be a valid and reliable instrument (24) with internal consistency coeffi- cients ranging from 0.70 to 0.90 (26). The TFEQ was administered before the video clip. The reliability of the total measure in the present sample was α = 0.90, and the reliability of the restraint, disinhibition, and hunger subscales were 0.77, 0.84, and 0.85, respectively. The Beck Depression Inventory (BDI) (27) consists of 21 items that assess depressive symptoms (e.g., I feel utterly worthless) on a scale from 0 to 3. Higher scores reflect more severe levels of depression, with a BDI score of ≥20 indicating moderate to severe depression. The BDI has demonstrated high internal consistency in both psychiatric, as well as community samples (mean coefficient = 0.87) (27,28). The BDI has also shown strong test–retest reliability, and high construct validity (27). The BDI was administered before the video clip and the reliability of this measure in the present sample was α = 0.92. The Fat Phobia Scale (shortened form) was adapted from the original Fat Phobia Scale (29). The shortened version of the Fat Phobia Scale lists 14 pairs of adjectives that may be used to describe overweight or obese individuals (e.g., attractive/unattractive, lazy/industrious). Participants are asked to indicate how well each adjective describes overweight people on a 5-point likert scale. The Fat Phobia Scale has exhibited strong reli- ability, as well as concurrent validity with the original version (29). Total scores range from 1 to 5; a score of 5 represents the greatest amount of fat phobia. The Fat Phobia Scale was administered to participants both before and following the video clips. The reliability of this measure in the present sample was α = 0.89. The Positive Affect Negative Affect Schedule (PANAS) (30) is a 20-item scale that measures participants’ positive and negative affect along a number of dimensions. Participants are asked to indicate to what extent they feel a certain way (e.g., alert, enthusiastic, distressed, scared) on a 5-point likert scale. Both the positive affect and negative affect sub- scales range from 10 to 50. The PANAS is highly internally consistent and has strong convergent and discriminant validity (30). The PANAS may be used as a trait version or may be used to assess state affect (when prefaced with “right now” or “in this moment”). The PANAS was administered to assess affect both before, and after, the video clips, and thus, the “state” instructions were employed. Cronbach’s α of the total measure in the present sample was 0.80; α’s = 0.90 and 0.80, for the positive and negative subscales, respectively. BMI was calculated from height and weight which were both measured by the experimenter at the conclusion of the study using a stadiometer and digital scale. Blood pressure was assessed using an automatic blood pressure cuff. statistical analysis All analyses were conducted using SPSS for Windows, 17.0 (SPSS, Chicago, IL). All tests were two-tailed; P values ≤0.05 were considered significant. ANOVA’s were conducted to assess baseline differences and to evaluate the success of randomization on balancing key vari- ables between groups. All significant differences were followed up with Bonferroni Hochberg post-hoc tests. To maximize statistical power, planned contrasts were performed to evaluate a priori hypotheses about group differences following the videos. These contrasts tested whether overweight participants who watched the stigmatizing video experienced increased negative affect, fat phobia, and blood pressure, and decreased positive affect following the video when compared to the other groups. A 2 × 2 analysis of covariance was used to test the main effects of weight status and video type, as well as the interac- tion between weight status and video type on caloric consumption while controlling for key covariates. results sample characteristics Seventy-four women (mean age 31.71 ± 12.72 years) com- pleted the study. The sample was divided into both overweight (BMI ≥25, n = 34) and normal-weight women (18.5 ≤ BMI ≤ 24.9, n = 40). The mean BMI of the overweight women was 31.63 ± 6.17, whereas the mean BMI of the normal-weight women was 21.34 ± 1.89. The demographic distribution was 50% white, 27% African American, 14% Asian American, 8% Hispanic, and 1% Native American. One individual in the Normal Weight/Neutral condition revealed she had not eaten anything in the past 24 h due to lack of food security; therefore, her data were excluded from analyses. Another individual from the Normal Weight/Neutral group had a BMI (18.3) that categorized her as underweight. Analyses did not differ when this individual was removed, thus her data are included (see Table 1 for baseline descriptive statistics of relevant variables). To assess for outliers, relevant variables were converted to standardized scores. Standardized scores ≥±2.5 were consid- ered outliers (31). Conversion to standardized scores revealed that in the caloric consumption variable, there were four uni- variate outliers (three in the Overweight/Stigma group, and one in the Overweight/Neutral group) who consumed far more calories than the rest of their respective group. These out- liers were transformed according to the convention outlined by Tabachnick and Fidell (31). Their raw scores on caloric consumption were transformed to the next highest score from their respective group plus one unit to bring them closer to the distribution. All subsequent analyses of caloric consumption employ these four outliers’ transformed data. Baseline differences between groups Between-group differences in baseline variables were assessed to determine relevant variables to control for in subsequent analyses. Significant differences between the four groups were found in BMI, age, depression, disinhibition, systolic blood pressure, diastolic blood pressure, and pulse (see Table 1). None of the other variables were found to be significantly dif- ferent among the groups. Bonferroni post-hoc tests revealed that participants in the Overweight/Neutral group reported greater baseline depres- sion than the Normal Weight/Neutral group (P = 0.036), and higher baseline blood pressure than both normal weight groups (P < 0.01). The Overweight/Stigma group had sig- nificantly higher baseline pulse than the Normal Weight/ Neutral group (P = 0.01). Post-hoc tests did not reveal any other significant baseline differences between groups (see Table 1). Although the groups were randomly assigned and strati- fied by BMI (two groups were overweight (BMI ≥25 kg/m2) and two groups were normal weight (BMI <25 kg/m2)), the Overweight/Stigma group had a higher mean BMI than the Overweight/Neutral group (P < 0.01) (see Table 1). The two normal weight groups did not differ in mean BMI. correlation analyses Correlations be