Eating Behaviors 15 (2014) 595–598
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Eating Behaviors
Personality characteristics in surgery seeking and non-surgery seeking obese individuals compared to non-obese controls Dea S. Stenbæk a,d, Liv V. Hjordt a,d, Mette E. Haahr a,d, Dorthe Worm b, Dorthe L. Hansen b, Erik L. Mortensen c, Gitte M. Knudsen a,d,⁎ a
Center for Integrated Molecular Brain Imaging, Blegdamsvej 9, 2100 Copenhagen, Rigshospitalet, University of Copenhagen, Denmark Department of Endocrinology, Hvidovre University Hospital, Denmark Institute of Public Health and Center for Healthy Aging, University of Copenhagen, Denmark d Neurobiology Research Unit, Blegdamsvej 9, 2100Copenhagen, Rigshospitalet, University of Copenhagen, Denmark b c
a r t i c l e
i n f o
Article history: Received 4 February 2014 Received in revised form 13 May 2014 Accepted 21 August 2014 Available online 28 August 2014 Keywords: Personality NEO PI-R Obesity Bariatric surgery Mental health
a b s t r a c t It is currently unknown what makes some obese individuals opt for bariatric surgery whereas others choose not to. The aim of this study was to examine whether personality characteristics differed between obese individuals signed up for Roux-en-Y gastric bypass (RYGB) (N = 30) and obese individuals not seeking RYGB (N = 30) compared to non-obese controls (N = 30). All participants completed the NEO Personality Inventory—Revised. The obese RYGB group displayed higher levels of Neuroticism and borderline lower levels of Extraversion compared to the obese non-RYGB and the non-obese group, while the two latter groups did not differ in terms of personality. The Neuroticism domain and possibly the Extraversion domain may therefore be worthwhile to consider in future studies investigating the outcome of bariatric surgery. © 2014 Published by Elsevier Ltd.
1. Introduction1 The prevalence of obesity among children and adults has increased dramatically all over the world. Obesity is associated with medical complications (Mun, Blackburn, & Matthews, 2001; Wadden & Stunkard, 2002; Wadden, Stunkard, & Berkowitz, 2005) and psychiatric illnesses, such as depression, anxiety, and personality disorders (Berkowitz & Fabricatore, 2011; Faith et al., 2011; Petry, Barry, Pietrzak, & Wagner, 2008). Psychological effects of obesity are pervasive (Puhl & Brownell, 2001, 2003; Puhl & Heuer, 2009; Teixeira & Budd, 2010), suggesting that obesity is associated with severe impediments to mental health (Marchesini et al., 2003; Mather, Cox, Enns, & Sareen, 2009; Novak & Brownell, 2011; Ransom, Ashton, Windover, & Heinberg, 2010). The stress–obesity hypothesis posits that chronic inability to regulate arousal states leads to activation of stress-mediated networks in the brain causing behavioural changes in preference and consumption of food (Bjorntorp, 2001; Dallman, Pecoraro, & la Fleur, 2005; Dallman et al., 2006; Kyrou, Chrousos, & Tsigos, 2006; Moore & Cunningham, 2012).
⁎ Corresponding author at: Neurobiology Research Unit, Section 6931, Rigshospitalet, University of Copenhagen, Blegdamsvej 9, DK-2100 Copenhagen, Denmark. Tel.: + 45 35456712; fax: +45 35456713. E-mail addresses: [email protected] (D.S. Stenbæk), [email protected] (L.V. Hjordt), [email protected] (E.L. Mortensen), [email protected] (G.M. Knudsen). 1 Roux-en-Y gastric bypass (RYGB).
http://dx.doi.org/10.1016/j.eatbeh.2014.08.008 1471-0153/© 2014 Published by Elsevier Ltd.
Thus, personality characteristics (e.g. Neuroticism), which predispose the individual to chronic stress may affect susceptibility to obesity (Elfhag & Lundh, 2007; Fassino, Piero, Gramaglia, & Abbate-Daga, 2004; McCann, 2011; Ryden et al., 2003; Sullivan, Cloninger, Przybeck, & Klein, 2007; Sutin, Ferrucci, Zonderman, & Terracciano, 2011). According to McCrae and Costa (2003), personality can be empirically described in terms of a five-factor model comprising five major domains of personality: Neuroticism (e.g. impulsiveness, vulnerability to stress, and negative emotionality), Extraversion (e.g. sociability, activity, and positive emotionality), Openness (e.g. receptiveness to new ideas and experiences), Agreeableness (e.g. trusting attitudes, generousness, and concern for others), and Conscientiousness (e.g. compliance, organizational skills, and achievement striving). For the purpose of measuring these domains they developed the widely used NEO Personality Inventory (NEO PI-R). However, only few studies have used the NEO PI-R to examine trait-correlates to obesity and bariatric surgery (Elfhag & Lundh, 2007; Sutin et al., 2011), and none have to our knowledge previously applied this inventory to describe personality characteristics of sub-groups within the obese population. This is important since there is evidence of heterogeneity within the obese population; treatment seekers reported higher levels of distress compared to nontreatment seekers (Fitzgibbon, Stolley, & Kirschenbaum, 1993) and obese surgery patients were characterised as more anxiety prone and impulsive compared to obese individuals undergoing conventional treatment (Ryden et al., 2003).
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Building on Ryden et al.'s (2003) findings, we therefore for the first time examined whether personality traits as assessed by the NEO PI-R differed between obese individuals seeking Roux-en-Y gastric bypass (RYGB) and obese individuals not seeking RYGB compared to nonobese controls. Knowledge about the personality characteristics of surgery seekers may be important to determine factors of importance for successful treatment outcome. We hypothesized that the obese RYGB group would be characterised by: 1) higher levels of Neuroticism and impulsiveness and 2) lower levels of Extraversion and Conscientiousness, and we further hypothesized that the obese non-RYGB group would report 3) intermediate levels on these measures. 2. Methods 2.1. Participants Thirty RYGB candidates (22 females) aged 30.0–64.9 years with a mean Body Mass Index (BMI) of 39.5 ± 2.8 (range: 33.3–43.8) participated in the study. Thirty obese non-RYGB seeking individuals were matched on age, gender, and BMI, mean BMI of 38.5 ± 5.5 (range: 31.1–58.5), and thirty non-obese controls with a mean BMI of 23.2 ± 1.8 (range: 20.5–28.0) were matched on age and gender from a large research database at Neurobiology Research Unit, Rigshospitalet, Denmark. The inclusion criterion for the obese non-RYGB seeking participants was no current weight loss programme, which was checked by phone. RYGB candidates were recruited by invitation at regular information meetings held in a plenum at the Department of Endocrinology, Hvidovre University Hospital, Denmark, approximately 6 months prior to RYGB. Exclusion criteria for all participants were current or previous neurological disease, severe somatic illness, substance abuse or severe dyslexia. All participants signed an informed consent form. Demographic information is presented in Table 1. 2.2. Measures Body weight and body height were measured to the nearest 0.1 kg and nearest cm, respectively. BMI was calculated by dividing body weight with height squared (kg/m2). Educational scores were rated on a 5-point Likert scale; 1 (no vocational degree), 2 (b2 years of vocational education), 3 (2–4 years of vocational secondary education), 4 (2–4 years of academic education including a prior high school degree),and 5 (N 4 years of academic education including a prior high school degree). The Danish version of the NEO PI-R (Costa & Mccrae, 2004) was used to assess personality. The NEO PI-R measures five major domains of personality: Neuroticism, Extraversion, Openness, Agreeableness, and Conscientiousness and for each domain six facets or concrete traits. It consists of 240 items rated on a 5-point Likert scale from 0 (strongly disagree) to 4 (strongly agree). The scores on the items loading on each personality domain are added to a total raw Table 1 Group differences in demographic data. Measures
Gender (F/M) Age (years) BMI (kg/m2) Educational level
RYGB (N = 30)
Non-RYGB (N = 30)
Non-obese (N = 30)
Mean ± SD
Mean ± SD
Mean ± SD
22/8 43.0 ± 9.6 39.5 ± 2.8 2.6 ± 1.2⁎
22/8 43.1 ± 10.9 38.5 ± 5.5 3.5 ± 1.3a
22/8 42.8 ± 11.5 23.2 ± 1.8⁎⁎ 3.7 ± 1.3b
Note: RYGB: Obese individuals signed up for Roux-en-Y gastric bypass; non-RYGB: obese individuals not seeking Roux-en-Y gastric bypass. a Information about educational levels was missing for three participants (N = 27). b Information about educational levels was missing for two participants (N = 28). ⁎⁎ The non-obese group had significantly lower BMI compared to the obese groups (p b 0.001). ⁎ The RYGB group had significantly lower educational levels compared to the non-obese group (p b 0.010).
score, which was used in the presented analyses. All participants completed the NEO PI-R.
2.3. Statistics Demographic data were analysed using analysis of variance (ANOVA) or Mann–Whitney U test for skewed data and chi-square tests (χ2) were used for categorical data. Between-group differences were examined with analysis of covariance (ANCOVA), adjusted for age, and gender. Internal consistency was evaluated with Cronbach's α coefficients. To account for multiple comparisons, a Bonferroni correction was applied for each set of analyses (i.e. adjusted significance levels were set at 0.01 (0.05 / 5) for between-group comparisons of personality domains and 0.0167 (0.05 / 3) for contrast comparisons). To determine the magnitude of group differences, effect sizes (as indicated by partial η2) were calculated. Outliers were defined as ±3 standard deviations (SD) from the group mean and were substituted to either lower or upper bound of the group 95% confidence interval, but this did not change the results. All statistical analyses were performed in SPSS (20.0).
3. Results 3.1. Group differences in demographics and personality characteristics Average age and female to male ratios across the three groups were similar. The obese groups did not differ significantly in educational levels, but the obese RYGB group had lower educational levels than the non-obese group. Furthermore, the obese groups were similar with regard to BMI, but obviously differed from the non-obese group (Table 1). Internal consistency coefficients for the five domains were high: Neuroticism, α = 0.93; Extraversion, α = 0.88; Openness, α = 0.89; Agreeableness, α = 0.88; and Conscientiousness, α = 0.88. The unadjusted mean scores (±SD) and group differences for the five NEO PI-R domains and facets with group differences obtained from contrast comparisons are presented in Table 2.
3.1.1. Neuroticism Adjusted mean differences between the three groups were significant. Contrasts revealed that the obese RYGB group presented with significantly higher Neuroticism scores compared to the obese non-RYGB and non-obese groups, while these two groups did not differ. The obese RYGB group reported significantly higher scores on the facets: anxiety, angry-hostility, depression and self-consciousness compared to the obese non-RYGB and non-obese groups (all p-values ≤ 0.001). 3.1.2. Extraversion Significant adjusted mean differences were found between the three groups. Contrasts showed that the obese RYGB group presented with significantly lower Extraversion scores compared to the obese nonRYGB group, but it did not differ from the non-obese group. The obese RYGB group reported significantly lower scores on the facets gregariousness (relative to the obese non-RYGB and non-obese groups), assertiveness and positive emotions (relative to the non-RYGB group), and activity (relative to the non-obese controls) (all p-values b 0.05). No significant adjusted group differences were found for the Openness, Agreeableness, and Conscientiousness domains and the observed effect sizes for the Neuroticism and Extraversion domains were medium to large (Table 2). In post hoc ANCOVAs, educational level was included as a covariate. This did not change the significant results of our main analyses for the Neuroticism domain (p = 0.003, partial η2 = 0.14), but overall group differences for the Extraversion domain were only borderline significant (p = 0.073, partial η2 = 0.06).
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Table 2 Group differences in personality characteristics. Measures
Neuroticism Anxiety Angry hostility Depression Self-consciousness Impulsivity Vulnerability Extraversion Warmth Gregariousness Assertiveness Activity Excitement-seeking Positive emotions Openness Agreeableness Conscientiousness
RYGB (1) (N = 30)
Non-RYGB (2) (N = 30)
Non-obese (3) (N = 30)
Group comparisons
Mean ± SD
Mean ± SD
Mean ± SD
p-Values, partial η2
93.4 15.37 14.1 17.0 17.4 18.9 10.7 106.4 22.3 16.4 14.7 17.6 14.6 19.3 106.3 123.1 112.8
74.2 11.6 10.5 11.4 13.2 18.0 9.4 120.1 24.2 19.5 17.8 19.1 16.7 22.7 114.0 123.1 116.6
72.2 10.3 10.2 11.5 14.4 16.4 9.3 115.6 23.3 19.6 15.2 20.3 16.1 21.2 115.9 129.3 121.3
pb p= pb pb p= p= p= p= p= p= p= p= p= p= p= p= p=
± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±
21.7 5.4 4.1 6.2 4.8 5.5 4.3 17.2 4.5 5.5 4.8 4.5 4.8 3.8 14.6 15.1 18.9
± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±
19.5 5.7 4.0 5.0 4.1 3.4 4.3 15.9 3.0 4.0 5.2 3.5 4.3 4.3 20.3 14.3 16.4
± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±
21.6 5.3 4.2 6.0 4.4 4.0 4.6 17.1 3.6 4.0 4.9 3.8 5.1 4.9 18.3 15.9 15.2
0.000, partial η2 0.001, partial η2 0.000, partial η2 0.000, partial η2 0.001, partial η2 0.084, partial η2 0.412, partial η2 0.006, partial η2 0.167, partial η2 0.009, partial η2 0.037, partial η2 0.036, partial η2 0.118, partial η2 0.013, partial η2 0.099, partial η2 0.170, partial η2 0.157, partial η2
Contrasts (1, 2, 3)
= = = = = = = = = = = = = = = = =
0.19 0.14 0.17 0.18 0.14 0.06 0.02 0.11 0.04 0.11 0.08 0.08 0.05 0.10 0.05 0.04 0.04
1 1 1 1 1
N N N N N
2,3 2,3 2,3 2,3 2,3
1b2 1 b 2, 3 1b2 1b3 1b2
Note: RYGB: Obese individuals signed up for Roux-en-Y gastric bypass; non-RYGB: obese individuals not seeking Roux-en-Y gastric bypass. Each row represents a separate ANCOVA analysis comparing group differences in personality adjusted for age and gender. Only facets of significant domains and significant contrasts are reported.
4. Discussion In partial agreement with our first hypothesis, obese individuals seeking RYGB had higher levels of Neuroticism compared to obese individuals who did not seek RYGB and non-obese controls. Contrary to our third hypothesis, however, no differences were observed between the obese non-RYGB and non-obese groups on this domain. In particular, seeking RYGB was associated with increased self-reporting of anxiety, anger and hostile attitudes, depression and increased self-awareness, supporting earlier findings for these characteristics among individuals seeking treatment for their obesity (Lykouras, 2008; Ryden et al., 2003). High Neuroticism is associated with reduced capacity to cope with stress (Gunthert, Cohen, & Armeli, 1999; Schneider, 2004) and according to the stress–obesity hypothesis chronic inability to regulate arousal states biases eating behaviours toward increased intake of high-energy and low-nutrient foods (Bjorntorp, 2001; Dallman et al., 2005, 2006; Kyrou et al., 2006; Moore & Cunningham, 2012). This is consistent with the high levels of Neuroticism observed for the obese RYGB group. However, no elevated levels of Neuroticism were present in the obese non-RYGB group, suggesting that Neuroticism may relate more to the treatment seeking aspect than to obesity as such. Previous studies have pointed to increased impulsiveness (a sub-facet of the Neuroticism domain) and lack of control and self-discipline as core characteristics associated with obesity (Mobbs, Crepin, Thiery, Golay, & Van der Linden, 2010; Mobbs, Van Der Linden, & Golay, 2007; Ryden et al., 2003, 2004; Sutin et al., 2011; Terracciano, Lockenhoff, Zonderman, Ferrucci, & Costa, 2008; Tice, Bratslavsky, & Baumeister, 2001). Contrary to our hypothesis, our results did not corroborate that increased impulsiveness or low Conscientiousness characterised either the obese RYGB or obese non-RYGB group when compared to a matched group of non-obese controls. In line with our second hypothesis, lower scores on the Extraversion domain were found to characterise the obese RYGB group, who displayed a social pattern of lower gregariousness and assertiveness accompanied by less frequent positive emotions and restricted activity. Relevant help seeking is an important aspect of regulating high arousal states, such as anger, stress and anxiety (Ozbay et al., 2007). Thus, obese individuals showing traits of lower sociability might be hampered in their relational strategies to overcome resistance and in their ability to establish and draw upon a supportive social network (Moore, Daniel, Paquet, Dube, & Gauvin, 2009; Olsson & Dahl, 2012). We speculate that obese individuals with low Extraversion scores combined with
high Neuroticism scores, sometimes referred to as Type D personality (Denollet, 2000), may be at increased risk of emotional and uncontrollable eating behaviours and hence more likely to opt for surgical intervention as supported by our results. A significant number of patients experience postsurgical problems with losing weight or maintaining weight loss (Anwar, Collins, Kow, & Toouli, 2008; Karlsson, Taft, Ryden, Sjostrom, & Sullivan, 2007; Marcus, Kalarchian, & Courcoulas, 2009). This could for some relate to the inherent difficulties associated with being a Type D personality and warrants further investigation into the importance of proper patient selection, educative counselling, and outcome of treatment. The obese RYGB group reported lower educational levels compared to the non-obese group. When educational level was included as a covariate in the analyses, the overall group differences for the Neuroticism domain remained significant, but were only borderline significant for the Extraversion domain. Pairwise analyses revealed that the obese RYGB group still presented with significantly lower Extraversion scores compared to the obese non-RYGB group (p = 0.002, partial η2 = 0.16). In a longitudinal study, adolescent self-reports of Neuroticism, Extraversion, Agreeableness, and Conscientiousness predicted occupational status 46 years later (Roberts, Kuncel, Shiner, Caspi, & Goldberg, 2007). In particular, high Neuroticism and low Extraversion were associated with lower occupational status, which perhaps could explain the shared variance between low Extraversion scores and educational level observed here. Taken together, our results suggest that in particular the Neuroticism domain and possibly also the Extraversion domain reflect important differences between obese individuals who seek RYGB and those who do not. These differences should therefore warrant caution when generalising from an obese sub-group to the obese population as a homogenous group. Recruitment of the obese individuals seeking RYGB was done by invitation at regular information meetings, while the obese non-RYGB seeking and non-obese individuals were matched from a large database. It is therefore possible that factors other than obesity and the treatment versus non-treatment aspect could have influenced our results. However, in our analyses we included age, gender, and educational level as covariates. The relatively small sample and cross-sectional design should also be considered. While our findings provide initial support for obese sub-group differences on the Neuroticism domain and possibly also the Extraversion domain, larger and longitudinal studies are needed in the future to replicate our results and to evaluate the potential prognostic effect of these domains on RYGB outcome and patient satisfaction.
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Role of funding sources The study was kindly supported by the Lundbeck Foundation (R71-A5679). The Lundbeck Foundation had no influence on the study design, analyses or interpretation of the results presented in the article. Contributors Dea S. Stenbæk: Acquired the data; managed literature searches; organized and conducted the statistical analyses; wrote the first draft of the manuscript; contributed substantially to analyses and interpretation of the results; and revised the manuscript critically for important intellectual content. Liv V. Hjordt: Contributed to conception and design of the study; involved in the statistical analyses; contributed substantially to analyses and interpretation of the results; and revised the manuscript critically for important intellectual content. Mette E. Haahr: Contributed to conception and design of the study; contributed considerably to analyses and interpretation of the results; and revised the manuscript critically for important intellectual content. Dorthe Worm: Carried out all medical examinations of the participants; recruited the participants; contributed considerably to analyses and interpretation of the results; and revised the manuscript critically for important intellectual content. Dorthe L. Hansent: Carried out all medical examinations of the participants; recruited the participants; contributed considerably to analyses and interpretation of the results; and revised the manuscript critically for important intellectual content. Erik L. Mortensen: Contributed substantially to conception and design of the study; considerably contributed to analyses and interpretation of data; and revised the manuscript critically for important intellectual content. Gitte Moos Knudsen: Contributed substantially to conception and design of the study; substantially contributed to analyses and interpretation of data;and revised the manuscript critically for important intellectual content. Conflict of interest All authors declare that they have no conflicts of interest. Acknowledgements The authors wish to thank all the participants and the staff at the Department of Endocrinology, Hvidovre University Hospital, Denmark.
References Anwar, M., Collins, J., Kow, L., & Toouli, J. (2008). Long-term efficacy of a low-pressure adjustable gastric band in the treatment of morbid obesity. Annals of Surgery, 247, 771–778. Berkowitz, R. I., & Fabricatore, A. N. (2011). Obesity, psychiatric status, and psychiatric medications. The Psychiatric Clinics of North America, 34, 747–764. Bjorntorp, P. (2001). Do stress reactions cause abdominal obesity and comorbidities? Obesity Reviews, 2, 73–86. Costa, P. T., & Mccrae, R. R. (2004). NEO PI-R. Manual—Clinical. Danish version by Skovdahl Hansen, H., Mortensen, E.L., & Schiøtz, H.K. Copenhagen: Dansk Psykologisk Forlag. Dallman, M. F., Pecoraro, N. C., & la Fleur, S. E. (2005). Chronic stress and comfort foods: Self-medication and abdominal obesity. Brain, Behavior, and Immunity, 19, 275–280. Dallman, M. F., Pecoraro, N. C., La Fleur, S. E., Warne, J. P., Ginsberg, A. B., Akana, S. F., et al. (2006). Glucocorticoids, chronic stress, and obesity. Progress in Brain Research, 153, 75–105. Denollet, J. (2000). Type D personality: A potential risk factor refined. Journal of Psychosomatic Research, 49, 255–266. Elfhag, K., & Lundh, L. G. (2007). TAS-20 alexithymia in obesity, and its links to personality. Scandinavian Journal of Psychology, 48, 391–398. Faith, M. S., Butryn, M., Wadden, T. A., Fabricatore, A., Nguyen, A.M., & Heymsfield, S. B. (2011). Evidence for prospective associations among depression and obesity in population-based studies. Obesity Reviews, 12, 438–453. Fassino, S., Piero, A., Gramaglia, C., & Abbate-Daga, G. (2004). Clinical, psychopathological and personality correlates of interoceptive awareness in anorexia nervosa, bulimia nervosa and obesity. Psychopathology, 37, 168–174. Fitzgibbon, M. L., Stolley, M. R., & Kirschenbaum, D. S. (1993). Obese people who seek treatment have different characteristics than those who do not seek treatment. Health Psychology, 12, 342–345. Gunthert, K. C., Cohen, L. H., & Armeli, S. (1999). The role of neuroticism in daily stress and coping. Journal of Personality and Social Psychology, 77, 1087–1100. Karlsson, J., Taft, C., Ryden, A., Sjostrom, L., & Sullivan, M. (2007). Ten-year trends in health-related quality of life after surgical and conventional treatment for severe obesity: The SOS intervention study. International Journal of Obesity, 31, 1248–1261. Kyrou, I., Chrousos, G. P., & Tsigos, C. (2006). Stress, visceral obesity, and metabolic complications. Annals of the New York Academy of Sciences, 1083, 77–110. Lykouras, L. (2008). Psychological profile of obese patients. Digestive Diseases, 26, 36–39.
Marchesini, G., Bellini, M., Natale, S., Belsito, C., Isacco, S., Nuccitelli, C., et al. (2003). Psychiatric distress and health-related quality of life in obesity. Diabetes, Nutrition & Metabolism, 16, 145–154. Marcus, M.D., Kalarchian, M.A., & Courcoulas, A. P. (2009). Psychiatric evaluation and follow-up of bariatric surgery patients. The American Journal of Psychiatry, 166, 285–291. Mather, A. A., Cox, B. J., Enns, M. W., & Sareen, J. (2009). Associations of obesity with psychiatric disorders and suicidal behaviors in a nationally representative sample. Journal of Psychosomatic Research, 66, 277–285. McCann, S. J. (2011). Personality and American state differences in obesity prevalence. Journal of Psychology, 145, 419–433. McCrae, R. R., & Costa, P. T. (2003). Personality in adulthood: A five-factor theory perspective. New York: Guilford Press. Mobbs, O., Crepin, C., Thiery, C., Golay, A., & Van der Linden, M. (2010). Obesity and the four facets of impulsivity. Patient Education and Counseling, 79, 372–377. Mobbs, O., Van Der Linden, M., & Golay, A. (2007). Impulsivity—Is one of the factors responsible for obesity? Revue Médicale Suisse, 3, 850–853. Moore, C. J., & Cunningham, S. A. (2012). Social position, psychological stress, and obesity: A systematic review. Journal Academy Nutrition Dietary, 112, 518–526. Moore, S., Daniel, M., Paquet, C., Dube, L., & Gauvin, L. (2009). Association of individual network social capital with abdominal adiposity, overweight and obesity. Journal of Public Health (Oxford, England), 31, 175–183. Mun, E. C., Blackburn, G. L., & Matthews, J. B. (2001). Current status of medical and surgical therapy for obesity. Gastroenterology, 120, 669–681. Novak, N. L., & Brownell, K. D. (2011). Obesity: A public health approach. The Psychiatric Clinics of North America, 34, 895–909. Olsson, I., & Dahl, A. A. (2012). Avoidant personality problems—Their association with somatic and mental health, lifestyle, and social network. A community-based study. Comprehensive Psychiatry, 53, 813–821. Ozbay, F., Johnson, D. C., Dimoulas, E., Morgan, C. A., Charney, D., & Southwick, S. (2007). Social support and resilience to stress: From neurobiology to clinical practice. Psychiatry, 4, 35–40. Petry, N. M., Barry, D., Pietrzak, R. H., & Wagner, J. A. (2008). Overweight and obesity are associated with psychiatric disorders: Results from the National Epidemiologic Survey on Alcohol and Related Conditions. Psychosomatic Medicine, 70, 288–297. Puhl, R., & Brownell, K. D. (2001). Bias, discrimination, and obesity. Obesity Research, 9, 788–805. Puhl, R., & Brownell, K. D. (2003). Ways of coping with obesity stigma: Review and conceptual analysis. Eating Behaviors, 4, 53–78. Puhl, R. M., & Heuer, C. A. (2009). The stigma of obesity: A review and update. Obesity (Silver Spring), 17, 941–964. Ransom, D., Ashton, K., Windover, A., & Heinberg, L. (2010). Internal consistency and validity assessment of SCL-90-R for bariatric surgery candidates. Surgery for Obesity and Related Diseases, 6, 622–627. Roberts, B. W., Kuncel, N. R., Shiner, R., Caspi, A., & Goldberg, L. R. (2007). The power of personality: The comparative validity of personality traits, socioeconomic status, and cognitive ability for predicting important life outcomes. Perspectives on Psychological Science, 2, 313–345. Ryden, A., Sullivan, M., Torgerson, J. S., Karlsson, J., Lindroos, A. K., & Taft, C. (2003). Severe obesity and personality: A comparative controlled study of personality traits. International Journal of Obesity and Related Metabolic Disorders, 27, 1534–1540. Ryden, A., Sullivan, M., Torgerson, J. S., Karlsson, J., Lindroos, A. K., & Taft, C. (2004). A comparative controlled study of personality in severe obesity: A 2-y follow-up after intervention. International Journal of Obesity and Related Metabolic Disorders, 28, 1485–1493. Schneider, T. R. (2004). The role of neuroticism on psychological and physiological stress responses. Journal of Experimental Social Psychology, 40, 795–804. Sullivan, S., Cloninger, C. R., Przybeck, T. R., & Klein, S. (2007). Personality characteristics in obesity and relationship with successful weight loss. International Journal of Obesity, 31, 669–674. Sutin, A.R., Ferrucci, L., Zonderman, A. B., & Terracciano, A. (2011). Personality and obesity across the adult life span. Journal of Personality and Social Psychology, 101, 579–592. Teixeira, M. E., & Budd, G. M. (2010). Obesity stigma: A newly recognized barrier to comprehensive and effective type 2 diabetes management. Journal of the American Academy of Nurse Practitioners, 22, 527–533. Terracciano, A., Lockenhoff, C. E., Zonderman, A. B., Ferrucci, L., & Costa, P. T., Jr. (2008). Personality predictors of longevity: Activity, emotional stability, and conscientiousness. Psychosomatic Medicine, 70, 621–627. Tice, D.M., Bratslavsky, E., & Baumeister, R. F. (2001). Emotional distress regulation takes precedence over impulse control: If you feel bad, do it! Journal of Personality and Social Psychology, 80, 53–67. Wadden, T. A., & Stunkard, A. J. (2002). Handbook of obesity treatment. New York: Guilford Press. Wadden, T. A., Stunkard, A. J., & Berkowitz, R. I. (2005). Obesity: A guide for mental health professionals. Philadelphia: Saunders.
Contents lists available at ScienceDirect
Eating Behaviors
Personality characteristics in surgery seeking and non-surgery seeking obese individuals compared to non-obese controls Dea S. Stenbæk a,d, Liv V. Hjordt a,d, Mette E. Haahr a,d, Dorthe Worm b, Dorthe L. Hansen b, Erik L. Mortensen c, Gitte M. Knudsen a,d,⁎ a
Center for Integrated Molecular Brain Imaging, Blegdamsvej 9, 2100 Copenhagen, Rigshospitalet, University of Copenhagen, Denmark Department of Endocrinology, Hvidovre University Hospital, Denmark Institute of Public Health and Center for Healthy Aging, University of Copenhagen, Denmark d Neurobiology Research Unit, Blegdamsvej 9, 2100Copenhagen, Rigshospitalet, University of Copenhagen, Denmark b c
a r t i c l e
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Article history: Received 4 February 2014 Received in revised form 13 May 2014 Accepted 21 August 2014 Available online 28 August 2014 Keywords: Personality NEO PI-R Obesity Bariatric surgery Mental health
a b s t r a c t It is currently unknown what makes some obese individuals opt for bariatric surgery whereas others choose not to. The aim of this study was to examine whether personality characteristics differed between obese individuals signed up for Roux-en-Y gastric bypass (RYGB) (N = 30) and obese individuals not seeking RYGB (N = 30) compared to non-obese controls (N = 30). All participants completed the NEO Personality Inventory—Revised. The obese RYGB group displayed higher levels of Neuroticism and borderline lower levels of Extraversion compared to the obese non-RYGB and the non-obese group, while the two latter groups did not differ in terms of personality. The Neuroticism domain and possibly the Extraversion domain may therefore be worthwhile to consider in future studies investigating the outcome of bariatric surgery. © 2014 Published by Elsevier Ltd.
1. Introduction1 The prevalence of obesity among children and adults has increased dramatically all over the world. Obesity is associated with medical complications (Mun, Blackburn, & Matthews, 2001; Wadden & Stunkard, 2002; Wadden, Stunkard, & Berkowitz, 2005) and psychiatric illnesses, such as depression, anxiety, and personality disorders (Berkowitz & Fabricatore, 2011; Faith et al., 2011; Petry, Barry, Pietrzak, & Wagner, 2008). Psychological effects of obesity are pervasive (Puhl & Brownell, 2001, 2003; Puhl & Heuer, 2009; Teixeira & Budd, 2010), suggesting that obesity is associated with severe impediments to mental health (Marchesini et al., 2003; Mather, Cox, Enns, & Sareen, 2009; Novak & Brownell, 2011; Ransom, Ashton, Windover, & Heinberg, 2010). The stress–obesity hypothesis posits that chronic inability to regulate arousal states leads to activation of stress-mediated networks in the brain causing behavioural changes in preference and consumption of food (Bjorntorp, 2001; Dallman, Pecoraro, & la Fleur, 2005; Dallman et al., 2006; Kyrou, Chrousos, & Tsigos, 2006; Moore & Cunningham, 2012).
⁎ Corresponding author at: Neurobiology Research Unit, Section 6931, Rigshospitalet, University of Copenhagen, Blegdamsvej 9, DK-2100 Copenhagen, Denmark. Tel.: + 45 35456712; fax: +45 35456713. E-mail addresses: [email protected] (D.S. Stenbæk), [email protected] (L.V. Hjordt), [email protected] (E.L. Mortensen), [email protected] (G.M. Knudsen). 1 Roux-en-Y gastric bypass (RYGB).
http://dx.doi.org/10.1016/j.eatbeh.2014.08.008 1471-0153/© 2014 Published by Elsevier Ltd.
Thus, personality characteristics (e.g. Neuroticism), which predispose the individual to chronic stress may affect susceptibility to obesity (Elfhag & Lundh, 2007; Fassino, Piero, Gramaglia, & Abbate-Daga, 2004; McCann, 2011; Ryden et al., 2003; Sullivan, Cloninger, Przybeck, & Klein, 2007; Sutin, Ferrucci, Zonderman, & Terracciano, 2011). According to McCrae and Costa (2003), personality can be empirically described in terms of a five-factor model comprising five major domains of personality: Neuroticism (e.g. impulsiveness, vulnerability to stress, and negative emotionality), Extraversion (e.g. sociability, activity, and positive emotionality), Openness (e.g. receptiveness to new ideas and experiences), Agreeableness (e.g. trusting attitudes, generousness, and concern for others), and Conscientiousness (e.g. compliance, organizational skills, and achievement striving). For the purpose of measuring these domains they developed the widely used NEO Personality Inventory (NEO PI-R). However, only few studies have used the NEO PI-R to examine trait-correlates to obesity and bariatric surgery (Elfhag & Lundh, 2007; Sutin et al., 2011), and none have to our knowledge previously applied this inventory to describe personality characteristics of sub-groups within the obese population. This is important since there is evidence of heterogeneity within the obese population; treatment seekers reported higher levels of distress compared to nontreatment seekers (Fitzgibbon, Stolley, & Kirschenbaum, 1993) and obese surgery patients were characterised as more anxiety prone and impulsive compared to obese individuals undergoing conventional treatment (Ryden et al., 2003).
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Building on Ryden et al.'s (2003) findings, we therefore for the first time examined whether personality traits as assessed by the NEO PI-R differed between obese individuals seeking Roux-en-Y gastric bypass (RYGB) and obese individuals not seeking RYGB compared to nonobese controls. Knowledge about the personality characteristics of surgery seekers may be important to determine factors of importance for successful treatment outcome. We hypothesized that the obese RYGB group would be characterised by: 1) higher levels of Neuroticism and impulsiveness and 2) lower levels of Extraversion and Conscientiousness, and we further hypothesized that the obese non-RYGB group would report 3) intermediate levels on these measures. 2. Methods 2.1. Participants Thirty RYGB candidates (22 females) aged 30.0–64.9 years with a mean Body Mass Index (BMI) of 39.5 ± 2.8 (range: 33.3–43.8) participated in the study. Thirty obese non-RYGB seeking individuals were matched on age, gender, and BMI, mean BMI of 38.5 ± 5.5 (range: 31.1–58.5), and thirty non-obese controls with a mean BMI of 23.2 ± 1.8 (range: 20.5–28.0) were matched on age and gender from a large research database at Neurobiology Research Unit, Rigshospitalet, Denmark. The inclusion criterion for the obese non-RYGB seeking participants was no current weight loss programme, which was checked by phone. RYGB candidates were recruited by invitation at regular information meetings held in a plenum at the Department of Endocrinology, Hvidovre University Hospital, Denmark, approximately 6 months prior to RYGB. Exclusion criteria for all participants were current or previous neurological disease, severe somatic illness, substance abuse or severe dyslexia. All participants signed an informed consent form. Demographic information is presented in Table 1. 2.2. Measures Body weight and body height were measured to the nearest 0.1 kg and nearest cm, respectively. BMI was calculated by dividing body weight with height squared (kg/m2). Educational scores were rated on a 5-point Likert scale; 1 (no vocational degree), 2 (b2 years of vocational education), 3 (2–4 years of vocational secondary education), 4 (2–4 years of academic education including a prior high school degree),and 5 (N 4 years of academic education including a prior high school degree). The Danish version of the NEO PI-R (Costa & Mccrae, 2004) was used to assess personality. The NEO PI-R measures five major domains of personality: Neuroticism, Extraversion, Openness, Agreeableness, and Conscientiousness and for each domain six facets or concrete traits. It consists of 240 items rated on a 5-point Likert scale from 0 (strongly disagree) to 4 (strongly agree). The scores on the items loading on each personality domain are added to a total raw Table 1 Group differences in demographic data. Measures
Gender (F/M) Age (years) BMI (kg/m2) Educational level
RYGB (N = 30)
Non-RYGB (N = 30)
Non-obese (N = 30)
Mean ± SD
Mean ± SD
Mean ± SD
22/8 43.0 ± 9.6 39.5 ± 2.8 2.6 ± 1.2⁎
22/8 43.1 ± 10.9 38.5 ± 5.5 3.5 ± 1.3a
22/8 42.8 ± 11.5 23.2 ± 1.8⁎⁎ 3.7 ± 1.3b
Note: RYGB: Obese individuals signed up for Roux-en-Y gastric bypass; non-RYGB: obese individuals not seeking Roux-en-Y gastric bypass. a Information about educational levels was missing for three participants (N = 27). b Information about educational levels was missing for two participants (N = 28). ⁎⁎ The non-obese group had significantly lower BMI compared to the obese groups (p b 0.001). ⁎ The RYGB group had significantly lower educational levels compared to the non-obese group (p b 0.010).
score, which was used in the presented analyses. All participants completed the NEO PI-R.
2.3. Statistics Demographic data were analysed using analysis of variance (ANOVA) or Mann–Whitney U test for skewed data and chi-square tests (χ2) were used for categorical data. Between-group differences were examined with analysis of covariance (ANCOVA), adjusted for age, and gender. Internal consistency was evaluated with Cronbach's α coefficients. To account for multiple comparisons, a Bonferroni correction was applied for each set of analyses (i.e. adjusted significance levels were set at 0.01 (0.05 / 5) for between-group comparisons of personality domains and 0.0167 (0.05 / 3) for contrast comparisons). To determine the magnitude of group differences, effect sizes (as indicated by partial η2) were calculated. Outliers were defined as ±3 standard deviations (SD) from the group mean and were substituted to either lower or upper bound of the group 95% confidence interval, but this did not change the results. All statistical analyses were performed in SPSS (20.0).
3. Results 3.1. Group differences in demographics and personality characteristics Average age and female to male ratios across the three groups were similar. The obese groups did not differ significantly in educational levels, but the obese RYGB group had lower educational levels than the non-obese group. Furthermore, the obese groups were similar with regard to BMI, but obviously differed from the non-obese group (Table 1). Internal consistency coefficients for the five domains were high: Neuroticism, α = 0.93; Extraversion, α = 0.88; Openness, α = 0.89; Agreeableness, α = 0.88; and Conscientiousness, α = 0.88. The unadjusted mean scores (±SD) and group differences for the five NEO PI-R domains and facets with group differences obtained from contrast comparisons are presented in Table 2.
3.1.1. Neuroticism Adjusted mean differences between the three groups were significant. Contrasts revealed that the obese RYGB group presented with significantly higher Neuroticism scores compared to the obese non-RYGB and non-obese groups, while these two groups did not differ. The obese RYGB group reported significantly higher scores on the facets: anxiety, angry-hostility, depression and self-consciousness compared to the obese non-RYGB and non-obese groups (all p-values ≤ 0.001). 3.1.2. Extraversion Significant adjusted mean differences were found between the three groups. Contrasts showed that the obese RYGB group presented with significantly lower Extraversion scores compared to the obese nonRYGB group, but it did not differ from the non-obese group. The obese RYGB group reported significantly lower scores on the facets gregariousness (relative to the obese non-RYGB and non-obese groups), assertiveness and positive emotions (relative to the non-RYGB group), and activity (relative to the non-obese controls) (all p-values b 0.05). No significant adjusted group differences were found for the Openness, Agreeableness, and Conscientiousness domains and the observed effect sizes for the Neuroticism and Extraversion domains were medium to large (Table 2). In post hoc ANCOVAs, educational level was included as a covariate. This did not change the significant results of our main analyses for the Neuroticism domain (p = 0.003, partial η2 = 0.14), but overall group differences for the Extraversion domain were only borderline significant (p = 0.073, partial η2 = 0.06).
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Table 2 Group differences in personality characteristics. Measures
Neuroticism Anxiety Angry hostility Depression Self-consciousness Impulsivity Vulnerability Extraversion Warmth Gregariousness Assertiveness Activity Excitement-seeking Positive emotions Openness Agreeableness Conscientiousness
RYGB (1) (N = 30)
Non-RYGB (2) (N = 30)
Non-obese (3) (N = 30)
Group comparisons
Mean ± SD
Mean ± SD
Mean ± SD
p-Values, partial η2
93.4 15.37 14.1 17.0 17.4 18.9 10.7 106.4 22.3 16.4 14.7 17.6 14.6 19.3 106.3 123.1 112.8
74.2 11.6 10.5 11.4 13.2 18.0 9.4 120.1 24.2 19.5 17.8 19.1 16.7 22.7 114.0 123.1 116.6
72.2 10.3 10.2 11.5 14.4 16.4 9.3 115.6 23.3 19.6 15.2 20.3 16.1 21.2 115.9 129.3 121.3
pb p= pb pb p= p= p= p= p= p= p= p= p= p= p= p= p=
± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±
21.7 5.4 4.1 6.2 4.8 5.5 4.3 17.2 4.5 5.5 4.8 4.5 4.8 3.8 14.6 15.1 18.9
± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±
19.5 5.7 4.0 5.0 4.1 3.4 4.3 15.9 3.0 4.0 5.2 3.5 4.3 4.3 20.3 14.3 16.4
± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±
21.6 5.3 4.2 6.0 4.4 4.0 4.6 17.1 3.6 4.0 4.9 3.8 5.1 4.9 18.3 15.9 15.2
0.000, partial η2 0.001, partial η2 0.000, partial η2 0.000, partial η2 0.001, partial η2 0.084, partial η2 0.412, partial η2 0.006, partial η2 0.167, partial η2 0.009, partial η2 0.037, partial η2 0.036, partial η2 0.118, partial η2 0.013, partial η2 0.099, partial η2 0.170, partial η2 0.157, partial η2
Contrasts (1, 2, 3)
= = = = = = = = = = = = = = = = =
0.19 0.14 0.17 0.18 0.14 0.06 0.02 0.11 0.04 0.11 0.08 0.08 0.05 0.10 0.05 0.04 0.04
1 1 1 1 1
N N N N N
2,3 2,3 2,3 2,3 2,3
1b2 1 b 2, 3 1b2 1b3 1b2
Note: RYGB: Obese individuals signed up for Roux-en-Y gastric bypass; non-RYGB: obese individuals not seeking Roux-en-Y gastric bypass. Each row represents a separate ANCOVA analysis comparing group differences in personality adjusted for age and gender. Only facets of significant domains and significant contrasts are reported.
4. Discussion In partial agreement with our first hypothesis, obese individuals seeking RYGB had higher levels of Neuroticism compared to obese individuals who did not seek RYGB and non-obese controls. Contrary to our third hypothesis, however, no differences were observed between the obese non-RYGB and non-obese groups on this domain. In particular, seeking RYGB was associated with increased self-reporting of anxiety, anger and hostile attitudes, depression and increased self-awareness, supporting earlier findings for these characteristics among individuals seeking treatment for their obesity (Lykouras, 2008; Ryden et al., 2003). High Neuroticism is associated with reduced capacity to cope with stress (Gunthert, Cohen, & Armeli, 1999; Schneider, 2004) and according to the stress–obesity hypothesis chronic inability to regulate arousal states biases eating behaviours toward increased intake of high-energy and low-nutrient foods (Bjorntorp, 2001; Dallman et al., 2005, 2006; Kyrou et al., 2006; Moore & Cunningham, 2012). This is consistent with the high levels of Neuroticism observed for the obese RYGB group. However, no elevated levels of Neuroticism were present in the obese non-RYGB group, suggesting that Neuroticism may relate more to the treatment seeking aspect than to obesity as such. Previous studies have pointed to increased impulsiveness (a sub-facet of the Neuroticism domain) and lack of control and self-discipline as core characteristics associated with obesity (Mobbs, Crepin, Thiery, Golay, & Van der Linden, 2010; Mobbs, Van Der Linden, & Golay, 2007; Ryden et al., 2003, 2004; Sutin et al., 2011; Terracciano, Lockenhoff, Zonderman, Ferrucci, & Costa, 2008; Tice, Bratslavsky, & Baumeister, 2001). Contrary to our hypothesis, our results did not corroborate that increased impulsiveness or low Conscientiousness characterised either the obese RYGB or obese non-RYGB group when compared to a matched group of non-obese controls. In line with our second hypothesis, lower scores on the Extraversion domain were found to characterise the obese RYGB group, who displayed a social pattern of lower gregariousness and assertiveness accompanied by less frequent positive emotions and restricted activity. Relevant help seeking is an important aspect of regulating high arousal states, such as anger, stress and anxiety (Ozbay et al., 2007). Thus, obese individuals showing traits of lower sociability might be hampered in their relational strategies to overcome resistance and in their ability to establish and draw upon a supportive social network (Moore, Daniel, Paquet, Dube, & Gauvin, 2009; Olsson & Dahl, 2012). We speculate that obese individuals with low Extraversion scores combined with
high Neuroticism scores, sometimes referred to as Type D personality (Denollet, 2000), may be at increased risk of emotional and uncontrollable eating behaviours and hence more likely to opt for surgical intervention as supported by our results. A significant number of patients experience postsurgical problems with losing weight or maintaining weight loss (Anwar, Collins, Kow, & Toouli, 2008; Karlsson, Taft, Ryden, Sjostrom, & Sullivan, 2007; Marcus, Kalarchian, & Courcoulas, 2009). This could for some relate to the inherent difficulties associated with being a Type D personality and warrants further investigation into the importance of proper patient selection, educative counselling, and outcome of treatment. The obese RYGB group reported lower educational levels compared to the non-obese group. When educational level was included as a covariate in the analyses, the overall group differences for the Neuroticism domain remained significant, but were only borderline significant for the Extraversion domain. Pairwise analyses revealed that the obese RYGB group still presented with significantly lower Extraversion scores compared to the obese non-RYGB group (p = 0.002, partial η2 = 0.16). In a longitudinal study, adolescent self-reports of Neuroticism, Extraversion, Agreeableness, and Conscientiousness predicted occupational status 46 years later (Roberts, Kuncel, Shiner, Caspi, & Goldberg, 2007). In particular, high Neuroticism and low Extraversion were associated with lower occupational status, which perhaps could explain the shared variance between low Extraversion scores and educational level observed here. Taken together, our results suggest that in particular the Neuroticism domain and possibly also the Extraversion domain reflect important differences between obese individuals who seek RYGB and those who do not. These differences should therefore warrant caution when generalising from an obese sub-group to the obese population as a homogenous group. Recruitment of the obese individuals seeking RYGB was done by invitation at regular information meetings, while the obese non-RYGB seeking and non-obese individuals were matched from a large database. It is therefore possible that factors other than obesity and the treatment versus non-treatment aspect could have influenced our results. However, in our analyses we included age, gender, and educational level as covariates. The relatively small sample and cross-sectional design should also be considered. While our findings provide initial support for obese sub-group differences on the Neuroticism domain and possibly also the Extraversion domain, larger and longitudinal studies are needed in the future to replicate our results and to evaluate the potential prognostic effect of these domains on RYGB outcome and patient satisfaction.
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Role of funding sources The study was kindly supported by the Lundbeck Foundation (R71-A5679). The Lundbeck Foundation had no influence on the study design, analyses or interpretation of the results presented in the article. Contributors Dea S. Stenbæk: Acquired the data; managed literature searches; organized and conducted the statistical analyses; wrote the first draft of the manuscript; contributed substantially to analyses and interpretation of the results; and revised the manuscript critically for important intellectual content. Liv V. Hjordt: Contributed to conception and design of the study; involved in the statistical analyses; contributed substantially to analyses and interpretation of the results; and revised the manuscript critically for important intellectual content. Mette E. Haahr: Contributed to conception and design of the study; contributed considerably to analyses and interpretation of the results; and revised the manuscript critically for important intellectual content. Dorthe Worm: Carried out all medical examinations of the participants; recruited the participants; contributed considerably to analyses and interpretation of the results; and revised the manuscript critically for important intellectual content. Dorthe L. Hansent: Carried out all medical examinations of the participants; recruited the participants; contributed considerably to analyses and interpretation of the results; and revised the manuscript critically for important intellectual content. Erik L. Mortensen: Contributed substantially to conception and design of the study; considerably contributed to analyses and interpretation of data; and revised the manuscript critically for important intellectual content. Gitte Moos Knudsen: Contributed substantially to conception and design of the study; substantially contributed to analyses and interpretation of data;and revised the manuscript critically for important intellectual content. Conflict of interest All authors declare that they have no conflicts of interest. Acknowledgements The authors wish to thank all the participants and the staff at the Department of Endocrinology, Hvidovre University Hospital, Denmark.
References Anwar, M., Collins, J., Kow, L., & Toouli, J. (2008). Long-term efficacy of a low-pressure adjustable gastric band in the treatment of morbid obesity. Annals of Surgery, 247, 771–778. Berkowitz, R. I., & Fabricatore, A. N. (2011). Obesity, psychiatric status, and psychiatric medications. The Psychiatric Clinics of North America, 34, 747–764. Bjorntorp, P. (2001). Do stress reactions cause abdominal obesity and comorbidities? Obesity Reviews, 2, 73–86. Costa, P. T., & Mccrae, R. R. (2004). NEO PI-R. Manual—Clinical. Danish version by Skovdahl Hansen, H., Mortensen, E.L., & Schiøtz, H.K. Copenhagen: Dansk Psykologisk Forlag. Dallman, M. F., Pecoraro, N. C., & la Fleur, S. E. (2005). Chronic stress and comfort foods: Self-medication and abdominal obesity. Brain, Behavior, and Immunity, 19, 275–280. Dallman, M. F., Pecoraro, N. C., La Fleur, S. E., Warne, J. P., Ginsberg, A. B., Akana, S. F., et al. (2006). Glucocorticoids, chronic stress, and obesity. Progress in Brain Research, 153, 75–105. Denollet, J. (2000). Type D personality: A potential risk factor refined. Journal of Psychosomatic Research, 49, 255–266. Elfhag, K., & Lundh, L. G. (2007). TAS-20 alexithymia in obesity, and its links to personality. Scandinavian Journal of Psychology, 48, 391–398. Faith, M. S., Butryn, M., Wadden, T. A., Fabricatore, A., Nguyen, A.M., & Heymsfield, S. B. (2011). Evidence for prospective associations among depression and obesity in population-based studies. Obesity Reviews, 12, 438–453. Fassino, S., Piero, A., Gramaglia, C., & Abbate-Daga, G. (2004). Clinical, psychopathological and personality correlates of interoceptive awareness in anorexia nervosa, bulimia nervosa and obesity. Psychopathology, 37, 168–174. Fitzgibbon, M. L., Stolley, M. R., & Kirschenbaum, D. S. (1993). Obese people who seek treatment have different characteristics than those who do not seek treatment. Health Psychology, 12, 342–345. Gunthert, K. C., Cohen, L. H., & Armeli, S. (1999). The role of neuroticism in daily stress and coping. Journal of Personality and Social Psychology, 77, 1087–1100. Karlsson, J., Taft, C., Ryden, A., Sjostrom, L., & Sullivan, M. (2007). Ten-year trends in health-related quality of life after surgical and conventional treatment for severe obesity: The SOS intervention study. International Journal of Obesity, 31, 1248–1261. Kyrou, I., Chrousos, G. P., & Tsigos, C. (2006). Stress, visceral obesity, and metabolic complications. Annals of the New York Academy of Sciences, 1083, 77–110. Lykouras, L. (2008). Psychological profile of obese patients. Digestive Diseases, 26, 36–39.
Marchesini, G., Bellini, M., Natale, S., Belsito, C., Isacco, S., Nuccitelli, C., et al. (2003). Psychiatric distress and health-related quality of life in obesity. Diabetes, Nutrition & Metabolism, 16, 145–154. Marcus, M.D., Kalarchian, M.A., & Courcoulas, A. P. (2009). Psychiatric evaluation and follow-up of bariatric surgery patients. The American Journal of Psychiatry, 166, 285–291. Mather, A. A., Cox, B. J., Enns, M. W., & Sareen, J. (2009). Associations of obesity with psychiatric disorders and suicidal behaviors in a nationally representative sample. Journal of Psychosomatic Research, 66, 277–285. McCann, S. J. (2011). Personality and American state differences in obesity prevalence. Journal of Psychology, 145, 419–433. McCrae, R. R., & Costa, P. T. (2003). Personality in adulthood: A five-factor theory perspective. New York: Guilford Press. Mobbs, O., Crepin, C., Thiery, C., Golay, A., & Van der Linden, M. (2010). Obesity and the four facets of impulsivity. Patient Education and Counseling, 79, 372–377. Mobbs, O., Van Der Linden, M., & Golay, A. (2007). Impulsivity—Is one of the factors responsible for obesity? Revue Médicale Suisse, 3, 850–853. Moore, C. J., & Cunningham, S. A. (2012). Social position, psychological stress, and obesity: A systematic review. Journal Academy Nutrition Dietary, 112, 518–526. Moore, S., Daniel, M., Paquet, C., Dube, L., & Gauvin, L. (2009). Association of individual network social capital with abdominal adiposity, overweight and obesity. Journal of Public Health (Oxford, England), 31, 175–183. Mun, E. C., Blackburn, G. L., & Matthews, J. B. (2001). Current status of medical and surgical therapy for obesity. Gastroenterology, 120, 669–681. Novak, N. L., & Brownell, K. D. (2011). Obesity: A public health approach. The Psychiatric Clinics of North America, 34, 895–909. Olsson, I., & Dahl, A. A. (2012). Avoidant personality problems—Their association with somatic and mental health, lifestyle, and social network. A community-based study. Comprehensive Psychiatry, 53, 813–821. Ozbay, F., Johnson, D. C., Dimoulas, E., Morgan, C. A., Charney, D., & Southwick, S. (2007). Social support and resilience to stress: From neurobiology to clinical practice. Psychiatry, 4, 35–40. Petry, N. M., Barry, D., Pietrzak, R. H., & Wagner, J. A. (2008). Overweight and obesity are associated with psychiatric disorders: Results from the National Epidemiologic Survey on Alcohol and Related Conditions. Psychosomatic Medicine, 70, 288–297. Puhl, R., & Brownell, K. D. (2001). Bias, discrimination, and obesity. Obesity Research, 9, 788–805. Puhl, R., & Brownell, K. D. (2003). Ways of coping with obesity stigma: Review and conceptual analysis. Eating Behaviors, 4, 53–78. Puhl, R. M., & Heuer, C. A. (2009). The stigma of obesity: A review and update. Obesity (Silver Spring), 17, 941–964. Ransom, D., Ashton, K., Windover, A., & Heinberg, L. (2010). Internal consistency and validity assessment of SCL-90-R for bariatric surgery candidates. Surgery for Obesity and Related Diseases, 6, 622–627. Roberts, B. W., Kuncel, N. R., Shiner, R., Caspi, A., & Goldberg, L. R. (2007). The power of personality: The comparative validity of personality traits, socioeconomic status, and cognitive ability for predicting important life outcomes. Perspectives on Psychological Science, 2, 313–345. Ryden, A., Sullivan, M., Torgerson, J. S., Karlsson, J., Lindroos, A. K., & Taft, C. (2003). Severe obesity and personality: A comparative controlled study of personality traits. International Journal of Obesity and Related Metabolic Disorders, 27, 1534–1540. Ryden, A., Sullivan, M., Torgerson, J. S., Karlsson, J., Lindroos, A. K., & Taft, C. (2004). A comparative controlled study of personality in severe obesity: A 2-y follow-up after intervention. International Journal of Obesity and Related Metabolic Disorders, 28, 1485–1493. Schneider, T. R. (2004). The role of neuroticism on psychological and physiological stress responses. Journal of Experimental Social Psychology, 40, 795–804. Sullivan, S., Cloninger, C. R., Przybeck, T. R., & Klein, S. (2007). Personality characteristics in obesity and relationship with successful weight loss. International Journal of Obesity, 31, 669–674. Sutin, A.R., Ferrucci, L., Zonderman, A. B., & Terracciano, A. (2011). Personality and obesity across the adult life span. Journal of Personality and Social Psychology, 101, 579–592. Teixeira, M. E., & Budd, G. M. (2010). Obesity stigma: A newly recognized barrier to comprehensive and effective type 2 diabetes management. Journal of the American Academy of Nurse Practitioners, 22, 527–533. Terracciano, A., Lockenhoff, C. E., Zonderman, A. B., Ferrucci, L., & Costa, P. T., Jr. (2008). Personality predictors of longevity: Activity, emotional stability, and conscientiousness. Psychosomatic Medicine, 70, 621–627. Tice, D.M., Bratslavsky, E., & Baumeister, R. F. (2001). Emotional distress regulation takes precedence over impulse control: If you feel bad, do it! Journal of Personality and Social Psychology, 80, 53–67. Wadden, T. A., & Stunkard, A. J. (2002). Handbook of obesity treatment. New York: Guilford Press. Wadden, T. A., Stunkard, A. J., & Berkowitz, R. I. (2005). Obesity: A guide for mental health professionals. Philadelphia: Saunders.
