Eating Behaviors 16 (2015) 13–16
Contents lists available at ScienceDirect
Eating Behaviors
A weighty issue: Explaining the association between body mass index and appearance-based social anxiety Kristen Titchener, Quincy J.J. Wong ⁎ Centre for Emotional Health, Department of Psychology, Macquarie University, Australia
a r t i c l e
i n f o
Article history: Received 7 April 2014 Received in revised form 14 August 2014 Accepted 23 October 2014 Available online 1 November 2014 Keywords: Social anxiety Appearance-based social anxiety Body mass index Obesity Body image dissatisfaction Emotional eating
a b s t r a c t Research has indicated that individuals who are overweight or obese are more likely to experience mental health difficulties. One line of research has indicated that body mass index (BMI) is positively associated with appearance-based social anxiety, rather than social anxiety more generally. However, there is a lack of research that has attempted to explain this association. Thus, the current study recruited an undergraduate sample (N = 90) and aimed (a) to replicate previous research by examining the associations between BMI, social anxiety, and appearance-based social anxiety and (b) to extend previous research by examining two potential mediators in the relationship between BMI and appearance-based social anxiety suggested in the literature (i.e., body image dissatisfaction and emotional eating). Analyses indicated that BMI was not associated with social anxiety but positively associated with appearance-based social anxiety. The association between BMI and appearance-based social anxiety was only mediated by body image dissatisfaction, and the model of these relationships emerged as the best fitting model relative to a plausible alternative model. The findings replicate and extend previous research on weight status and psychological factors and highlight the need for future longitudinal research on BMI, appearance-based social anxiety, and body image dissatisfaction so that interventions for obesity and weight loss maintenance programs can be ultimately enhanced. © 2014 Elsevier Ltd. All rights reserved.
1. Introduction Overweightness and obesity are world-wide physical health concerns that are associated with mental health difficulties (Petry, Barry, Pietrzak, & Wagner, 2008; Scott, Bruffaerts, Simon, Alonso, Angermeyer, de Girolamo, et al., 2008; World Health Organisation, 2000, 2013). Social anxiety disorder (SAD), a mental health concern characterised by an intense fear of social situations in which evaluation from others may occur (American Psychiatric Association, 2013), has been shown to be positively associated with obesity, particularly in females (see Gariepy, Nitka, & Schmitz, 2010, for a review). This finding suggests that females with a higher body mass index (BMI) have a greater likelihood of experiencing social-evaluative anxiety. This may be the case given one's weight is a characteristic observable by others, societal pressures to be thin (Stice, 2002), and weight-related prejudice and discrimination (Carr & Friedman, 2005; Puhl & Heuer, 2009). When obesity and SAD have been analysed in terms of their continuous variable equivalents (i.e., BMI and social anxiety levels), studies have shown that BMI is not associated with social anxiety level in female-only samples or predominantly female samples (e.g., Levinson et al., 2013; Mayer, Muris, Meesters, & Zimmermann-van Beuningen, ⁎ Corresponding author at: Centre for Emotional Health, Department of Psychology, Macquarie University, NSW 2109, Australia. Tel.: +61 2 9850 8053. E-mail address: [email protected] (Q.J.J. Wong).
http://dx.doi.org/10.1016/j.eatbeh.2014.10.005 1471-0153/© 2014 Elsevier Ltd. All rights reserved.
2009; Ostrovsky, Swencionis, Wylie-Rosett, & Isasi, 2013). Studies have instead shown a positive association between BMI and appearancebased social anxiety in female-only or predominantly female samples (e.g., Crocker, Sabiston, Kowalski, McDonough, & Kowalski, 2006; Diehl, Johnson, Rogers, & Petrie, 1998; Levinson et al., 2013). Some studies have failed to find the BMI and appearance-based social anxiety association (e.g., Levinson & Rodebaugh, 2011), although arguably these studies examined samples with a more even gender distribution. Overall, BMI appears most likely to be positively related to appearance-based social anxiety rather than general social anxiety in females. Appearancebased social anxiety may also play a role in the association between obesity and SAD given the lack of association between BMI and general social anxiety. To our knowledge, there are currently no studies that have explained the association between weight status and appearancebased social anxiety (see also Pagoto, Schneider, Appelhans, Curtin, & Hajduk, 2011). Body image dissatisfaction (BID) and emotional eating (EE) are two variables proposed in the literature that might explain this association (Barry, Pietrzak, & Petry, 2008; Friedman & Brownell, 1995; Gatineau & Dent, 2011; Scott, McGee, Wells, & Oakley Browne, 2008). The proposed mediating roles of BID and EE have not been explicitly tested in the literature, although BMI has been shown to be positively related to both BID (e.g., Jones, Vigfusdottir, & Lee, 2004; Paxton, Eisenberg, & Neumark-Sztainer, 2006) and EE (e.g., Clum, Rice, Broussard, Johnson, & Webber, 2014; Koenders & Van Strien, 2011),
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K. Titchener, Q.J.J. Wong / Eating Behaviors 16 (2015) 13–16
and appearance-based social anxiety has also been shown to be positively related to both BID (e.g., Hart et al., 2008; Levinson & Rodebaugh, 2012) and EE (e.g., Ostrovsky et al., 2013). The current study aimed (a) to replicate previous findings on the relationships between BMI, social anxiety, and appearance-based social anxiety and (b) to extend current research by examining the role of BID and EE in these relationships. We predicted that after controlling for potential confounding variables (see Method), BMI would be positively associated with appearance-based social anxiety but not general social anxiety. We further predicted that after controlling for potential confounders that (a) BMI would be positively associated with BID which would in turn be positively associated with appearance-based social anxiety and (b) appearance-based social anxiety would be positively associated with EE which would in turn be positively associated with BMI. We expected that in each of these cases the relationship between BMI and appearance-based social anxiety would disappear once BID or EE was taken into account. 2. Methods 2.1. Participants Ninety female undergraduates from six Australian universities participated in the study (mean age = 20.71, SD = 4.23; 67% normal weight [BMI 18.50–24.99], 25% overweight [BMI 25.00–29.99], 8% obese [BMI ≥30]) for course credit or as volunteers. 2.2. Measures The Demographic, Health, and Lifestyle Questionnaire (DHLQ) was developed for the current study to measure potential confounding variables: age, ethnicity, medical conditions, medications, exercise, smoking, and alcohol consumption (see Gariepy et al., 2010). Mood level, another potential confounder, was measured using the Depression Subscale of the Depression Anxiety Stress Scales (DASS-D; Lovibond & Lovibond, 1995). BMI was calculated from the weight (kg) and height (m) of participants measured with weight scales and a tape measure. Social anxiety was measured with the Social Phobia Scale (SPS; Mattick & Clarke, 1998), and the straightforwardly worded items of the Social Interactional Anxiety Scale (S-SIAS; Rodebaugh, Woods, & Heimberg, 2007). Appearance-based social anxiety was measured with the Social Appearance Anxiety Scale (SAAS; Hart et al., 2008) and the Physical Appearance Subscale of the Negative Self-Portrayal Scale (NSPS-PA; Moscovitch & Huyder, 2011). BID was assessed with the Body Dissatisfaction Subscale of the Eating Disorder Inventory (EDI-BD; Garner, Olmstead, & Polivy, 1983), and EE was measured using the Anxiety Subscale of the Emotional Eating Scale (EES-A; Arnow, Kenardy, & Agras, 1995). 2.3. Procedure Participants provided informed consent and completed the DHLQ and then the remaining questionnaires in a randomised order. Participants were subsequently asked to remove their shoes and their height and weight were recorded by a female experimenter. 2.4. Analyses A social anxiety composite measure was formed by converting SPS and S-SIAS raw scores (which correlated .71) to z scores and averaging the z scores (see Wong & Moulds, 2010). An appearance-based social anxiety composite measure was similarly formed using SAAS and NSPS-PA scores (which correlated .68). Given certain variables had non-normal distributions, bootstrapping analyses (Efron & Tibshirani, 1993; Preacher & Hayes, 2004) were conducted and used to test: (a) associations between potential confounders
and the main variables and (b) hypothesised associations and mediational (indirect) effects. We utilised a bootstrapping method with 1000 bootstrapped samples and bias-corrected confidence intervals (BCCI). The fit of mediational models tested was evaluated using several fit indices (Brown, 2006): the comparative fit index (CFI; values ≥ .90 suggest acceptable fit with higher values indicating better fit), the non-normed fit index (NNFI; values ≥ .90 suggest acceptable fit with higher values indicating better fit), the root mean square error of approximation (RMSEA; values ≤ .08 suggest acceptable fit with lower values indicating better fit), the standard root mean square residual (SRMR; values ≤ .08 suggest acceptable fit with lower values indicating better fit), and the Akaike information criterion (AIC; smaller values indicate better fit). 3. Results Table 1 shows descriptive statistics, correlations for the main variables, and results from the analysis of potential confounding variables. The significant relationships between potential confounders and the main variables were accounted for in subsequent analyses. 3.1. BMI, social anxiety, and appearance-based social anxiety Accounting for DASS-D, BMI was not significantly associated with the social anxiety composite, r = .11, 95% BCCI [− .12, .35], p = .36. Accounting for DASS-D and smoking frequency, BMI had a significant positive association with the appearance-based social anxiety composite, r = .21, 95% BCCI [.02, .40], p = .04. 3.2. The mediating role of BID and EE in the BMI and appearance-based social anxiety association The test of the mediating role of the EDI-BD (accounting for relevant potential confounders) indicated expected significant paths (see Panel A, Fig. 1). Importantly, the significant direct path from BMI to the appearance-based social anxiety composite became non-significant after the EDI-BD was accounted for. There was also a significant indirect effect from BMI to the appearance-based social anxiety composite via the EDI-BD, standardised indirect effect = .23, 95% BCCI [.11, .39], p b .01. The hypothesised mediational model demonstrated adequate to good fit with the data (CFI = .95, NNFI = .91, RMSEA = .08, SRMR = .08, AIC =38.43). The test of the mediating role of the EES-A (accounting for relevant potential confounders) indicated a significant path from the appearance-based social anxiety composite to the EES-A, β = .26, 95% BCCI [.07, .46], p b .01, but the path from the EES-A to BMI was nonsignificant, β = − .17, 95% BCCI [− .33, .01], p = .07. Thus, it was not possible to further test the mediating role of the EES-A in the BMI and appearance-based social anxiety association. 3.3. Post hoc analysis: considering plausible alternative models Given the mediating role of the EDI-BD in the BMI and appearancebased social anxiety association, we subsequently considered an alternative model that appeared most likely based on previous research (Gatineau & Dent, 2011): BMI has psychological consequences such that increased BMI leads to both BID and appearance-based social anxiety with the latter two constructs mutually influencing each other. A test of this model (accounting for relevant potential confounders) indicated expected significant paths (see Panel B, Fig. 1). However, this alternative model did not demonstrate acceptable fit (CFI = .91, NNFI = .85, RMSEA = .10, SRMR = .11, AIC = 41.35) and is less preferred when compared to the original hypothesised model (i.e., Panel A, Fig. 1).
K. Titchener, Q.J.J. Wong / Eating Behaviors 16 (2015) 13–16
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Table 1 Means, standard deviations, and zero-order correlations for the main variables and results from the analysis of potential confounding variables (N = 90). Main variables
Mean (SD)
1
1. BMI 2. SPS 3. S-SIAS 4. SAAS 5. NSPS-PA 6. EDI-BD 7. EES-A 8. SAC 9. ABSAC
24.05 (4.34) 15.57 (12.09) 17.56 (11.42) 35.64 (12.82) 16.52 (5.50) 10.66 (6.88) 7.81 (5.34) 0.00 (0.93) 0.00 (0.92)
– .16 .10 .30** .14 .51** −.09 .14 .24*
2 – .71** .68** .51** .38** .10 .93** .65**
3
– .55** .51** .34** .14 .93** .58**
4
– .68** .54** .21 .66** .92**
5
– .43** .32** .55** .92**
6
– .07 .39** .53**
7
– .13 .29**
8
Potential confounding variables significantly related to the main variable
– .66**
None (all ps N .06) – – – – Medication use, r = .23 [.01, .46] Ethnicity, r = −.26 [−.42, −.05] DASS-D, r = .45 [.22, .65] DASS-D, r = .49 [.30, .68], smoking frequency, r = −.14 [−.34, −.01]
Note. Values in square brackets in the far right column are the lower and upper bounds for the 95% bias-corrected confidence intervals. Potential confounding variables examined included: age, ethnicity, medical conditions, medications, exercise, smoking frequency, frequency of alcohol consumption, and DASS-D. Further details about the confounder analysis are available from the second author upon request. BMI = body mass index; SPS = Social Phobia Scale; S-SIAS = straightforwardly worded items of the SIAS; SAAS = Social Appearance Anxiety Scale; NSPS-PA = Negative Self-Portrayal Scale—Physical Appearance subscale; EDI-BD = Eating Disorders Inventory—Body Dissatisfaction subscale; EES-A = Emotional Eating Scale—Anxiety subscale; SAC = social anxiety composite; ABSAC = appearance-based social anxiety composite; DASS-D = Depression Anxiety Stress Scales—Depression subscale. *p b .05, **p b .01.
4. Discussion As predicted, after accounting for potential confounders, we found in a female undergraduate sample that BMI (a) was not significantly related to general social anxiety but (b) had a significant positive association with appearance-based social anxiety. The first finding replicates research that has shown BMI and social anxiety are not significantly related in predominantly female or female-only samples (e.g., Levinson et al., 2013), suggesting that social anxiety as a construct may be too broad to capture the specific social concerns of females with higher BMIs. The second finding replicates research that has shown a significant positive association between BMI and appearance-based social anxiety in predominantly female or female-only samples (e.g., Crocker et al., 2006), and supports the notion that females with higher BMIs are more likely
to have social concerns specifically when their weight and body may be salient to others (e.g., having their photo taken). Extending research on BMI, social anxiety, and appearance-based social anxiety, the current study provided the first explicit tests of BID and EE as mediators of the BMI and appearance-based social anxiety association. As predicted, BID fully mediated the relationship between BMI and appearance-based social anxiety. Additionally, the model of these relationships was superior to a plausible alternative model that involved the same three key variables. Although this BID result is cross-sectional, the finding raises the possibility that females with higher BMIs may only experience social anxiety in relation to their appearance because they are dissatisfied with their body image. The finding is also consistent with the view that one of the components of interventions for obesity and weight loss maintenance programs should address psychological targets including BID (e.g., Carraça et al., 2011; Harriger & Thompson, 2012; Ohsiek & Williams, 2011). Against prediction, EE was not a mediator in the BMI and appearance-based social anxiety association as the relationship between EE and BMI was not significant. These results contrast with studies that have found a positive association between EE and BMI (e.g., Koenders & Van Strien, 2011) and studies that have proposed EE as a mediator between BMI and psychological consequences (e.g., Scott, McGee et al., 2008). One possible explanation for why EE was not a mediator in the BMI and appearance-based social anxiety association in the current study is that participants who engaged in EE in response to appearance-based social anxiety subsequently performed activities to prevent weight gain (e.g., exercise, restricting further food intake). Future research will be needed to test this explanation. Limitations of this study should be noted. We utilised a convenience sample of undergraduates with only 33% of participants classified as overweight or obese and the cross-sectional nature of collected data prevented inferences about the causal relationship between variables. Future research should replicate the study using other samples (e.g., community samples) and examine BID as a mediator in the longitudinal relationship between BMI and appearance-based social anxiety.
5. Conclusions Fig. 1. The role of body image dissatisfaction in the association between BMI and appearancebased social anxiety (Panel A) and an alternative model involving BMI, body image dissatisfaction, and appearance-based social anxiety (Panel B). Note. Potential confounding variables (medication use, DASS-D, and smoking frequency) were accounted for in the analyses but are not represented in the diagrams for clarity. The broken line in Panel A denotes the significant association between BMI and the appearance-based social anxiety composite when the EDIBD was not accounted for. Values in square brackets are the lower and upper bounds for the 95% bias-corrected confidence intervals. BMI = body mass index; EDI-BD = Eating Disorders Inventory—Body Dissatisfaction subscale; ABSAC = appearance-based social anxiety composite.
Limitations notwithstanding, this study has demonstrated that for females with higher BMIs, appearance-based social anxiety appears to be more relevant than social anxiety in general, and appearance-based social anxiety may only occur for these individuals because of BID. This study has also highlighted the need for the continued examination of BMI, appearance-based social anxiety, and BID so that interventions for obesity and weight loss maintenance programs can be ultimately enhanced.
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K. Titchener, Q.J.J. Wong / Eating Behaviors 16 (2015) 13–16
Role of funding source This study was supported by a National Health and Medical Research Council (NHMRC) Early Career Fellowship (1037618) awarded to Dr. Quincy Wong. The NHMRC had no role in the study design, collection, analysis or interpretation of the data, writing the manuscript, or the decision to submit the paper for publication. Contributors Kristen Titchener and Quincy Wong each contributed to the design of the study, analysis of data, and manuscript preparation. Kristen Titchener also collected the data for the study. Both authors have approved the final manuscript. Conflict of interest The authors declare that they have no conflicts of interest.
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Contents lists available at ScienceDirect
Eating Behaviors
A weighty issue: Explaining the association between body mass index and appearance-based social anxiety Kristen Titchener, Quincy J.J. Wong ⁎ Centre for Emotional Health, Department of Psychology, Macquarie University, Australia
a r t i c l e
i n f o
Article history: Received 7 April 2014 Received in revised form 14 August 2014 Accepted 23 October 2014 Available online 1 November 2014 Keywords: Social anxiety Appearance-based social anxiety Body mass index Obesity Body image dissatisfaction Emotional eating
a b s t r a c t Research has indicated that individuals who are overweight or obese are more likely to experience mental health difficulties. One line of research has indicated that body mass index (BMI) is positively associated with appearance-based social anxiety, rather than social anxiety more generally. However, there is a lack of research that has attempted to explain this association. Thus, the current study recruited an undergraduate sample (N = 90) and aimed (a) to replicate previous research by examining the associations between BMI, social anxiety, and appearance-based social anxiety and (b) to extend previous research by examining two potential mediators in the relationship between BMI and appearance-based social anxiety suggested in the literature (i.e., body image dissatisfaction and emotional eating). Analyses indicated that BMI was not associated with social anxiety but positively associated with appearance-based social anxiety. The association between BMI and appearance-based social anxiety was only mediated by body image dissatisfaction, and the model of these relationships emerged as the best fitting model relative to a plausible alternative model. The findings replicate and extend previous research on weight status and psychological factors and highlight the need for future longitudinal research on BMI, appearance-based social anxiety, and body image dissatisfaction so that interventions for obesity and weight loss maintenance programs can be ultimately enhanced. © 2014 Elsevier Ltd. All rights reserved.
1. Introduction Overweightness and obesity are world-wide physical health concerns that are associated with mental health difficulties (Petry, Barry, Pietrzak, & Wagner, 2008; Scott, Bruffaerts, Simon, Alonso, Angermeyer, de Girolamo, et al., 2008; World Health Organisation, 2000, 2013). Social anxiety disorder (SAD), a mental health concern characterised by an intense fear of social situations in which evaluation from others may occur (American Psychiatric Association, 2013), has been shown to be positively associated with obesity, particularly in females (see Gariepy, Nitka, & Schmitz, 2010, for a review). This finding suggests that females with a higher body mass index (BMI) have a greater likelihood of experiencing social-evaluative anxiety. This may be the case given one's weight is a characteristic observable by others, societal pressures to be thin (Stice, 2002), and weight-related prejudice and discrimination (Carr & Friedman, 2005; Puhl & Heuer, 2009). When obesity and SAD have been analysed in terms of their continuous variable equivalents (i.e., BMI and social anxiety levels), studies have shown that BMI is not associated with social anxiety level in female-only samples or predominantly female samples (e.g., Levinson et al., 2013; Mayer, Muris, Meesters, & Zimmermann-van Beuningen, ⁎ Corresponding author at: Centre for Emotional Health, Department of Psychology, Macquarie University, NSW 2109, Australia. Tel.: +61 2 9850 8053. E-mail address: [email protected] (Q.J.J. Wong).
http://dx.doi.org/10.1016/j.eatbeh.2014.10.005 1471-0153/© 2014 Elsevier Ltd. All rights reserved.
2009; Ostrovsky, Swencionis, Wylie-Rosett, & Isasi, 2013). Studies have instead shown a positive association between BMI and appearancebased social anxiety in female-only or predominantly female samples (e.g., Crocker, Sabiston, Kowalski, McDonough, & Kowalski, 2006; Diehl, Johnson, Rogers, & Petrie, 1998; Levinson et al., 2013). Some studies have failed to find the BMI and appearance-based social anxiety association (e.g., Levinson & Rodebaugh, 2011), although arguably these studies examined samples with a more even gender distribution. Overall, BMI appears most likely to be positively related to appearance-based social anxiety rather than general social anxiety in females. Appearancebased social anxiety may also play a role in the association between obesity and SAD given the lack of association between BMI and general social anxiety. To our knowledge, there are currently no studies that have explained the association between weight status and appearancebased social anxiety (see also Pagoto, Schneider, Appelhans, Curtin, & Hajduk, 2011). Body image dissatisfaction (BID) and emotional eating (EE) are two variables proposed in the literature that might explain this association (Barry, Pietrzak, & Petry, 2008; Friedman & Brownell, 1995; Gatineau & Dent, 2011; Scott, McGee, Wells, & Oakley Browne, 2008). The proposed mediating roles of BID and EE have not been explicitly tested in the literature, although BMI has been shown to be positively related to both BID (e.g., Jones, Vigfusdottir, & Lee, 2004; Paxton, Eisenberg, & Neumark-Sztainer, 2006) and EE (e.g., Clum, Rice, Broussard, Johnson, & Webber, 2014; Koenders & Van Strien, 2011),
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and appearance-based social anxiety has also been shown to be positively related to both BID (e.g., Hart et al., 2008; Levinson & Rodebaugh, 2012) and EE (e.g., Ostrovsky et al., 2013). The current study aimed (a) to replicate previous findings on the relationships between BMI, social anxiety, and appearance-based social anxiety and (b) to extend current research by examining the role of BID and EE in these relationships. We predicted that after controlling for potential confounding variables (see Method), BMI would be positively associated with appearance-based social anxiety but not general social anxiety. We further predicted that after controlling for potential confounders that (a) BMI would be positively associated with BID which would in turn be positively associated with appearance-based social anxiety and (b) appearance-based social anxiety would be positively associated with EE which would in turn be positively associated with BMI. We expected that in each of these cases the relationship between BMI and appearance-based social anxiety would disappear once BID or EE was taken into account. 2. Methods 2.1. Participants Ninety female undergraduates from six Australian universities participated in the study (mean age = 20.71, SD = 4.23; 67% normal weight [BMI 18.50–24.99], 25% overweight [BMI 25.00–29.99], 8% obese [BMI ≥30]) for course credit or as volunteers. 2.2. Measures The Demographic, Health, and Lifestyle Questionnaire (DHLQ) was developed for the current study to measure potential confounding variables: age, ethnicity, medical conditions, medications, exercise, smoking, and alcohol consumption (see Gariepy et al., 2010). Mood level, another potential confounder, was measured using the Depression Subscale of the Depression Anxiety Stress Scales (DASS-D; Lovibond & Lovibond, 1995). BMI was calculated from the weight (kg) and height (m) of participants measured with weight scales and a tape measure. Social anxiety was measured with the Social Phobia Scale (SPS; Mattick & Clarke, 1998), and the straightforwardly worded items of the Social Interactional Anxiety Scale (S-SIAS; Rodebaugh, Woods, & Heimberg, 2007). Appearance-based social anxiety was measured with the Social Appearance Anxiety Scale (SAAS; Hart et al., 2008) and the Physical Appearance Subscale of the Negative Self-Portrayal Scale (NSPS-PA; Moscovitch & Huyder, 2011). BID was assessed with the Body Dissatisfaction Subscale of the Eating Disorder Inventory (EDI-BD; Garner, Olmstead, & Polivy, 1983), and EE was measured using the Anxiety Subscale of the Emotional Eating Scale (EES-A; Arnow, Kenardy, & Agras, 1995). 2.3. Procedure Participants provided informed consent and completed the DHLQ and then the remaining questionnaires in a randomised order. Participants were subsequently asked to remove their shoes and their height and weight were recorded by a female experimenter. 2.4. Analyses A social anxiety composite measure was formed by converting SPS and S-SIAS raw scores (which correlated .71) to z scores and averaging the z scores (see Wong & Moulds, 2010). An appearance-based social anxiety composite measure was similarly formed using SAAS and NSPS-PA scores (which correlated .68). Given certain variables had non-normal distributions, bootstrapping analyses (Efron & Tibshirani, 1993; Preacher & Hayes, 2004) were conducted and used to test: (a) associations between potential confounders
and the main variables and (b) hypothesised associations and mediational (indirect) effects. We utilised a bootstrapping method with 1000 bootstrapped samples and bias-corrected confidence intervals (BCCI). The fit of mediational models tested was evaluated using several fit indices (Brown, 2006): the comparative fit index (CFI; values ≥ .90 suggest acceptable fit with higher values indicating better fit), the non-normed fit index (NNFI; values ≥ .90 suggest acceptable fit with higher values indicating better fit), the root mean square error of approximation (RMSEA; values ≤ .08 suggest acceptable fit with lower values indicating better fit), the standard root mean square residual (SRMR; values ≤ .08 suggest acceptable fit with lower values indicating better fit), and the Akaike information criterion (AIC; smaller values indicate better fit). 3. Results Table 1 shows descriptive statistics, correlations for the main variables, and results from the analysis of potential confounding variables. The significant relationships between potential confounders and the main variables were accounted for in subsequent analyses. 3.1. BMI, social anxiety, and appearance-based social anxiety Accounting for DASS-D, BMI was not significantly associated with the social anxiety composite, r = .11, 95% BCCI [− .12, .35], p = .36. Accounting for DASS-D and smoking frequency, BMI had a significant positive association with the appearance-based social anxiety composite, r = .21, 95% BCCI [.02, .40], p = .04. 3.2. The mediating role of BID and EE in the BMI and appearance-based social anxiety association The test of the mediating role of the EDI-BD (accounting for relevant potential confounders) indicated expected significant paths (see Panel A, Fig. 1). Importantly, the significant direct path from BMI to the appearance-based social anxiety composite became non-significant after the EDI-BD was accounted for. There was also a significant indirect effect from BMI to the appearance-based social anxiety composite via the EDI-BD, standardised indirect effect = .23, 95% BCCI [.11, .39], p b .01. The hypothesised mediational model demonstrated adequate to good fit with the data (CFI = .95, NNFI = .91, RMSEA = .08, SRMR = .08, AIC =38.43). The test of the mediating role of the EES-A (accounting for relevant potential confounders) indicated a significant path from the appearance-based social anxiety composite to the EES-A, β = .26, 95% BCCI [.07, .46], p b .01, but the path from the EES-A to BMI was nonsignificant, β = − .17, 95% BCCI [− .33, .01], p = .07. Thus, it was not possible to further test the mediating role of the EES-A in the BMI and appearance-based social anxiety association. 3.3. Post hoc analysis: considering plausible alternative models Given the mediating role of the EDI-BD in the BMI and appearancebased social anxiety association, we subsequently considered an alternative model that appeared most likely based on previous research (Gatineau & Dent, 2011): BMI has psychological consequences such that increased BMI leads to both BID and appearance-based social anxiety with the latter two constructs mutually influencing each other. A test of this model (accounting for relevant potential confounders) indicated expected significant paths (see Panel B, Fig. 1). However, this alternative model did not demonstrate acceptable fit (CFI = .91, NNFI = .85, RMSEA = .10, SRMR = .11, AIC = 41.35) and is less preferred when compared to the original hypothesised model (i.e., Panel A, Fig. 1).
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Table 1 Means, standard deviations, and zero-order correlations for the main variables and results from the analysis of potential confounding variables (N = 90). Main variables
Mean (SD)
1
1. BMI 2. SPS 3. S-SIAS 4. SAAS 5. NSPS-PA 6. EDI-BD 7. EES-A 8. SAC 9. ABSAC
24.05 (4.34) 15.57 (12.09) 17.56 (11.42) 35.64 (12.82) 16.52 (5.50) 10.66 (6.88) 7.81 (5.34) 0.00 (0.93) 0.00 (0.92)
– .16 .10 .30** .14 .51** −.09 .14 .24*
2 – .71** .68** .51** .38** .10 .93** .65**
3
– .55** .51** .34** .14 .93** .58**
4
– .68** .54** .21 .66** .92**
5
– .43** .32** .55** .92**
6
– .07 .39** .53**
7
– .13 .29**
8
Potential confounding variables significantly related to the main variable
– .66**
None (all ps N .06) – – – – Medication use, r = .23 [.01, .46] Ethnicity, r = −.26 [−.42, −.05] DASS-D, r = .45 [.22, .65] DASS-D, r = .49 [.30, .68], smoking frequency, r = −.14 [−.34, −.01]
Note. Values in square brackets in the far right column are the lower and upper bounds for the 95% bias-corrected confidence intervals. Potential confounding variables examined included: age, ethnicity, medical conditions, medications, exercise, smoking frequency, frequency of alcohol consumption, and DASS-D. Further details about the confounder analysis are available from the second author upon request. BMI = body mass index; SPS = Social Phobia Scale; S-SIAS = straightforwardly worded items of the SIAS; SAAS = Social Appearance Anxiety Scale; NSPS-PA = Negative Self-Portrayal Scale—Physical Appearance subscale; EDI-BD = Eating Disorders Inventory—Body Dissatisfaction subscale; EES-A = Emotional Eating Scale—Anxiety subscale; SAC = social anxiety composite; ABSAC = appearance-based social anxiety composite; DASS-D = Depression Anxiety Stress Scales—Depression subscale. *p b .05, **p b .01.
4. Discussion As predicted, after accounting for potential confounders, we found in a female undergraduate sample that BMI (a) was not significantly related to general social anxiety but (b) had a significant positive association with appearance-based social anxiety. The first finding replicates research that has shown BMI and social anxiety are not significantly related in predominantly female or female-only samples (e.g., Levinson et al., 2013), suggesting that social anxiety as a construct may be too broad to capture the specific social concerns of females with higher BMIs. The second finding replicates research that has shown a significant positive association between BMI and appearance-based social anxiety in predominantly female or female-only samples (e.g., Crocker et al., 2006), and supports the notion that females with higher BMIs are more likely
to have social concerns specifically when their weight and body may be salient to others (e.g., having their photo taken). Extending research on BMI, social anxiety, and appearance-based social anxiety, the current study provided the first explicit tests of BID and EE as mediators of the BMI and appearance-based social anxiety association. As predicted, BID fully mediated the relationship between BMI and appearance-based social anxiety. Additionally, the model of these relationships was superior to a plausible alternative model that involved the same three key variables. Although this BID result is cross-sectional, the finding raises the possibility that females with higher BMIs may only experience social anxiety in relation to their appearance because they are dissatisfied with their body image. The finding is also consistent with the view that one of the components of interventions for obesity and weight loss maintenance programs should address psychological targets including BID (e.g., Carraça et al., 2011; Harriger & Thompson, 2012; Ohsiek & Williams, 2011). Against prediction, EE was not a mediator in the BMI and appearance-based social anxiety association as the relationship between EE and BMI was not significant. These results contrast with studies that have found a positive association between EE and BMI (e.g., Koenders & Van Strien, 2011) and studies that have proposed EE as a mediator between BMI and psychological consequences (e.g., Scott, McGee et al., 2008). One possible explanation for why EE was not a mediator in the BMI and appearance-based social anxiety association in the current study is that participants who engaged in EE in response to appearance-based social anxiety subsequently performed activities to prevent weight gain (e.g., exercise, restricting further food intake). Future research will be needed to test this explanation. Limitations of this study should be noted. We utilised a convenience sample of undergraduates with only 33% of participants classified as overweight or obese and the cross-sectional nature of collected data prevented inferences about the causal relationship between variables. Future research should replicate the study using other samples (e.g., community samples) and examine BID as a mediator in the longitudinal relationship between BMI and appearance-based social anxiety.
5. Conclusions Fig. 1. The role of body image dissatisfaction in the association between BMI and appearancebased social anxiety (Panel A) and an alternative model involving BMI, body image dissatisfaction, and appearance-based social anxiety (Panel B). Note. Potential confounding variables (medication use, DASS-D, and smoking frequency) were accounted for in the analyses but are not represented in the diagrams for clarity. The broken line in Panel A denotes the significant association between BMI and the appearance-based social anxiety composite when the EDIBD was not accounted for. Values in square brackets are the lower and upper bounds for the 95% bias-corrected confidence intervals. BMI = body mass index; EDI-BD = Eating Disorders Inventory—Body Dissatisfaction subscale; ABSAC = appearance-based social anxiety composite.
Limitations notwithstanding, this study has demonstrated that for females with higher BMIs, appearance-based social anxiety appears to be more relevant than social anxiety in general, and appearance-based social anxiety may only occur for these individuals because of BID. This study has also highlighted the need for the continued examination of BMI, appearance-based social anxiety, and BID so that interventions for obesity and weight loss maintenance programs can be ultimately enhanced.
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Role of funding source This study was supported by a National Health and Medical Research Council (NHMRC) Early Career Fellowship (1037618) awarded to Dr. Quincy Wong. The NHMRC had no role in the study design, collection, analysis or interpretation of the data, writing the manuscript, or the decision to submit the paper for publication. Contributors Kristen Titchener and Quincy Wong each contributed to the design of the study, analysis of data, and manuscript preparation. Kristen Titchener also collected the data for the study. Both authors have approved the final manuscript. Conflict of interest The authors declare that they have no conflicts of interest.
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