Obesity
Brief Cutting Edge Report EPIDEMIOLOGY/GENETICS
Perceived Weight Discrimination and C-Reactive Protein Angelina R. Sutin1, Yannick Stephan2, Martina Luchetti3 and Antonio Terracciano1
Objective: Perceived weight discrimination has been linked to health outcomes, including risk of obesity. Less is known about how discrimination is associated with intermediate physiological markers of health, such as systemic inflammation. This research examined the association between weight discrimination and C-reactive protein (CRP) and whether it varied by participants’ body mass index (BMI). Methods: Cross-sectional design using data from the Health and Retirement Study. Among participants who were overweight or obese (N 5 7,394), regression analysis was used to test for an association between weight discrimination and CRP and whether this association was moderated by BMI. Similar associations among seven other attributions for discrimination were tested. Results: The association between weight discrimination and CRP varied as a function of BMI: At BMI between the thresholds for overweight and obesity (BMI 25–30), weight discrimination was associated with higher circulating levels of CRP; there was no association between weight discrimination and CRP as BMI approached Class 3 obesity (BMI 40). A similar pattern emerged for discrimination based on a physical disability, but not for the other attributions for discrimination (e.g., race, age). Conclusions: Weight discrimination is associated with higher circulating CRP, an association that is moderated by BMI. Obesity (2014) 22, 1959–1961. doi:10.1002/oby.20789
Introduction It is not uncommon for individuals who are overweight or obese to be discriminated against on the basis of their weight (1). These experiences are not just unpleasant but also have significant health consequences. Individuals who are obese who experience weight discrimination, for example, decline more rapidly in mobility over 10 years (2) and are more likely to remain obese over a four-year follow-up period (3) than individuals who are obese who do not experience such discrimination. Although this growing literature implicates perceived weight discrimination in health outcomes, less research has focused on its association with intermediate physiological markers that may contribute to declines in health. Inflammatory markers, particularly C-reactive protein (CRP), are of great interest due to their role in significant health conditions and links to psychosocial factors. CRP is a marker of systemic inflammation that is an independent predictor of cardiovascular disease and diabetes (4,5). CRP has also been associated with psychological factors, such as the development of depression (6), and social factors, including perceived discrimination. For example, older African Americans who report more experiences with discrimination have
higher levels of CRP (7). Whether this association extends to weight discrimination is not yet known. The present study examines the association between perceived weight discrimination and CRP. Because of its strong association with obesity, we tested whether body mass index (BMI) moderated the association between weight discrimination and this inflammatory marker, in addition to testing for a main effect. Since individuals who are overweight or obese more commonly report weight discrimination than individuals who are more lean, we focus on those with a BMI 25.
Methods Participants Participants were drawn from the Health and Retirement Study (HRS), a longitudinal study of Americans ages 50 and older (8). Starting in 2006, HRS implemented an enhanced face-to-face interview that included a psychosocial questionnaire (9) and biomarker assessment (10). Half of the HRS participants completed this interview in 2006; the other half completed it in 2008; we used the combined 2006 and 2008 assessments for analysis. We selected participants who had BMIs above the threshold for
1
Florida State University College of Medicine, Tallahassee, Florida, USA. Correspondence: Angelina R. Sutin ([email protected]) 2 Department of Sport Sciences, Psychology and Medicine, University of Montpellier, Montpellier, France 3 Department of Psychology, University of Bologna, Bologna, Italy
Funding agency: The Health and Retirement Study is sponsored by the National Institute on Aging (NIA-U01AG009740) and conducted by the University of Michigan. Author contributions: ARS conceived the study and analyzed the data. YS, ML, and AT provided critical feedback and direction. All authors wrote the paper and had final approval of the submitted version. Disclosure: The authors declare no conflict of interest. Additional Supporting Information may be found in the online version of this article. Received: 21 February 2014; Accepted: 29 April 2014; Published online 14 May 2014. doi:10.1002/oby.20789
www.obesityjournal.org
Obesity | VOLUME 22 | NUMBER 9 | SEPTEMBER 2014
1959
Obesity
Discrimination and CRP Sutin et al.
TABLE 1 Linear regression analysis predicting log CRP from
perceived weight discrimination Log CRP Predictor
b
SE
b
Age Age squared Sex Race (Black) Race (Other) Education BMI Weight discrimination BMI 3 weight discrimination
20.01 0.00 0.27 0.21 20.14 20.03 0.29 0.14 20.09
0.01 0.01 0.03 0.04 0.08 0.01 0.02 0.06 0.04
20.01 0.00 0.12b 0.06b 20.02 20.09b 0.25b 0.04ba 20.04b
N57,394. CRP 5 C-reactive protein, BMI 5 body mass index, b 5 unstandardized beta coefficient, SE 5 standard error. a Significant in the fully adjusted model. b P < 0.05
overweight (i.e., 25), completed the questionnaire, and had valid CRP values. A total of 7,394 participants met these criteria (Mage 5 67.23, SD 5 9.74; 57% female; 12% African American; 3% other race).
and their interaction, controlling for age, age squared, sex, ethnicity, and education. Although weight discrimination and BMI were correlated (r 5 0.32), the variance inflation factor was only 1.16, which is well below the 2.50 threshold for concern about multicollinearity. We followed a similar procedure for the other attributions to determine whether this effect was specific to weight discrimination or if there was a more general pattern for attributions for discrimination.
Results A total of 695 participants (9.4%) reported that they had been discriminated against because of their weight. As expected, BMI was a strong predictor of CRP. The association between weight discrimination and CRP was qualified by an interaction with BMI (Table 1). Among participants with relatively lower BMI, having experienced weight discrimination was associated with higher levels of inflammation. Among participants with relatively higher BMI, however, weight discrimination was unrelated to inflammation (Figure 1). This interaction was fairly specific to weight discrimination. With one exception—physical disability—the other attributions for discrimination were unrelated to CRP, and the interactions between each attribution and BMI were not significant (Supporting Information Table 1). Similar to weight discrimination, perceived discrimination based on a physical disability was associated with more inflammation at relatively lower, but not higher, BMI.
Measures Perceived discrimination.
Participants rated their experience of everyday discrimination (11) and attributed those experiences to personal characteristics, including weight (12). Participants could also have attributed those experiences to their ancestry, sex, race, age, physical disability, other aspects of physical appearance, and/or sexual orientation. Although single-item measures are not ideal, they have been used successfully to track trends in weight discrimination (1) and to document the correlates of weight bias (3).
Discussion The present research adds to the growing literature that documents the association between perceived weight discrimination and physical health. Weight discrimination is not only related to significant health outcomes, such as mobility (2) and obesity (3), but also to
High sensitivity C-reactive protein. To obtain a blood sample, the participant’s finger was cleansed with an alcohol swab, pricked with a sterile lancet, and the blood droplets were placed on specially treated filter paper. Blood samples were assayed for CRP at the University of Vermont using a standard ELIZA assay (see ref. 10 for details). Due to the skewed distribution, we took the natural log to normalize the distribution. The correlation between the raw and transformed CRP was 0.68.
Body mass index. Trained staff took anthropometric measurements during the face-to-face interview. Height was measured without shoes and recorded to the nearest quarter inch. Weight was measured without shoes and with light clothing using a Healthometer 830 kiloliter scale (Jarden Corporation, Rye, NY) and recorded to the nearest half pound (up to 330 pounds). BMI was calculated as kg/m2 (M 5 31.43, SD 5 5.04).
Analytic strategy We used Aiken and West’s (13) method for interactions to test whether BMI moderated the association between weight discrimination and inflammation among participants who were overweight and obese. Specifically, we used linear regression to predict logtransformed CRP from weight discrimination, mean-centered BMI,
1960
Obesity | VOLUME 22 | NUMBER 9 | SEPTEMBER 2014
FIGURE 1 Association between perceived weight discrimination and log CRP estimated from the regression equation, plotted at the mean BMI of the sample (Mean BMI 5 31.42, SD 5 5.04) and 1 standard deviation below (BMI 26) and above (BMI 36) the sample mean.
www.obesityjournal.org
Brief Cutting Edge Report
Obesity
EPIDEMIOLOGY/GENETICS
intermediate physiological markers of health. In the present study, individuals who perceived weight discrimination had more systemic inflammation, but this association varied as a function of BMI. Among participants with relatively lower BMI (BMI closer to 30), discrimination was associated with higher CRP, whereas it was unrelated to CRP among participants with relatively higher BMI (BMI closer to 40). There is a strong linear association between obesity and inflammation—as BMI increases, so does CRP—and there may be a point at which higher CRP is due primarily to adiposity. That is, most of the variance may be attributed to BMI, overwhelming the effect of psychological or social factors on inflammation. At relatively lower BMI, however, weight discrimination is associated with higher CRP. The behavioral coping mechanisms associated with perceived weight discrimination may contribute to this association. Individuals who perceive discrimination based on their weight, for example, tend to overeat to cope with the stress and also avoid physical activity (14). Experimental manipulations of stigma also suggest that individuals who are overweight consume more calories following a stigmatizing experience (15). Since diet and physical activity are both associated with inflammation (16,17), these behavioral ways of coping with weight discrimination may contribute to the association with higher inflammation. These coping strategies may also be more specific to weight discrimination than to other forms of discrimination. The present research indicated that the association between weight discrimination and CRP is moderated by BMI; CRP may also be a mediator between weight discrimination and obesity. We have shown previously that perceiving weight discrimination is associated with risk of becoming and remaining obese over four years (3). Since inflammatory markers have been associated prospectively with weight gain among adults (18), higher CRP may be one pathway through which discrimination contributes to the subsequent development and maintenance of obesity. That is, for individuals who are overweight, this higher level of CRP may then contribute to the association between weight discrimination and risk for obesity. The present study documents the moderator part of this pathway; future research needs to test the proposed mediator pathway. With one exception, discrimination based on attributions to other personal characteristics was unrelated to CRP. Similar to weight discrimination, the effect of discrimination based on a physical disability on CRP was only apparent among individuals with relatively lower BMI. In the current research, however, we were unable to control for who had a disability, which may mean that the physical condition associated with the disability may be more strongly associated with CRP than the social experience of discrimination. In addition, it was surprising that attributions for discrimination to the other six characteristics were unrelated to CRP. Given that previous research has found discrimination based on other characteristics to be associated with inflammation (7) and obesity (19), more research is needed before concluding that weight and physical disability are the only attributions for discrimination that are associated with higher inflammation. The present study had several strengths, including a large and fairly diverse sample. There are also limitations that need to be addressed in future research. First, our sample was primarily older adults; this association should be tested in a younger population. Second, the
www.obesityjournal.org
data were cross-sectional; longitudinal data are needed to test the temporal relations between discrimination and inflammation. Third, future research could test the mechanisms hypothesized to contribute to the discrimination–CRP link, such as whether diet and physical activity mediate the association between weight discrimination and CRP. Finally, future research could also test the hypothesis that inflammation contributes to the association between weight discrimination and the development and maintenance of obesity. This research is a step toward identifying physiological mechanisms that link discrimination to physical health. O
Acknowledgements HRS data is publically available at http://hrsonline.isr.umich.edu/. C 2014 The Obesity Society V
References 1. Andreyeva T, Puhl RM, Brownell KD. Changes in perceived weight discrimination among Americans, 1995–1996 through 2004–2006 Obesity 2008;16:1129-1134. 2. Schafer MH, Ferraro KF. The stigma of obesity: Does perceived weight discrimination affect identity and physical health? Soc Psychol Q 2011;74:76-97. 3. Sutin AR, Terracciano A. Perceived weight discrimination and obesity. PLoS One 2013;8:e70048. 4. Danesh J, Wheeler JG, Hirschfield GM, et al. C-reactive protein and other circulating markers of inflammation in the prediction of coronary heart disease. N Engl J Med 2004;350:1387-1397. 5. Pradhan AD, Manson JE, Rifai N, et al. C-reactive protein, interleukin 6, and risk of developing type 2 diabetes mellitus. JAMA 2001;286:327-334. 6. Wium-Andersen MK, Ørsted DD, Nielsen SF, Nordestgaard BG. Elevated Creactive protein levels, psychological distress, and depression in 73,131 individuals. JAMA Psychiatry 2013;70:176-184. 7. Lewis TT, Aiello AE, Leurgans S, Kelly J, Barnes LL. Self-reported experiences of everyday discrimination are associated with elevated C-reactive protein levels in older African-American adults. Brain Behav Immun 2010;24:438-443. 8. Health and Retirement Study, 2006 and 2010 Core public use dataset. Produced and distributed by the University of Michigan with funding from the National Institute on Aging (grant number NIA U01AG009740). Ann Arbor, MI, 2012. 9. Clarke P, Fisher G, House J, Smith J, Weir D. Guide to Content of the HRS Psychosocial Leave-Behind Participant Lifestyle Questionnaires: 2004 & 2006. Ann Arbor, MI: University of Michigan, 2008. 10. Crimmins E, Faul J, Kim JK, et al. Documentation of Biomarkers in the 2006 and 2008 Health and Retirement Study. Ann Arbor, MI: Survey Research Center University of Michigan; 2013. 11. Williams DR, Yu Y, Jackson JS, Anderson NB. Racial differences in physical and mental health. Socio-economic status, stress and discrimination. J Health Psychol 1997;2:335-351. 12. Kessler RC, Mickelson KD, Williams DR. The prevalence, distribution, and mental health correlates of perceived discrimination in the United States. J Health Soc Behav 1999;40:208-230. 13. Aiken LS, West SG. Multiple Regression: Testing and Interpreting Interactions. Thousand Oaks, CA: Sage; 1991. 14. Vartanian LR, Novak SA. Internalized societal attitudes moderate the impact of weight stigma on avoidance of exercise. Obesity 2011;19:757-762. 15. Schvey NA, Puhl RM, Brownell KD. The impact of weight stigma on caloric consumption. Obesity 2011;19:1957-1962. 16. Fung TT, McCullough ML, Newby PK, et al. Diet-quality scores and plasma concentrations of markers of inflammation and endothelial dysfunction. Am J Clin Nutr 2005;82:163-73. 17. Healy GN, Matthews CE, Dunstan DW, Winkler EA, Owen N. Sedentary time and cardio-metabolic biomarkers in US adults: NHANES 2003-06. Eur Heart J 2011; 32:590-597. 18. Duncan BB, Schmidt MI, Chambless LE, Folsom AR, Carpenter M, Heiss G. Fibrinogen, other putative markers of inflammation, and weight gain in middle-aged adults—The ARIC study. Atherosclerosis Risk in Communities. Obes Res 2000;8: 279-286. 19. Cozier YC, Yu J, Coogan PF, Bethea TN, Rosenberg L, Palmer JR. Racism, Segregation, and Risk of Obesity in the Black Women’s Health Study. Am J Epidemiol 2014;179:875-883.
Obesity | VOLUME 22 | NUMBER 9 | SEPTEMBER 2014
1961
Brief Cutting Edge Report EPIDEMIOLOGY/GENETICS
Perceived Weight Discrimination and C-Reactive Protein Angelina R. Sutin1, Yannick Stephan2, Martina Luchetti3 and Antonio Terracciano1
Objective: Perceived weight discrimination has been linked to health outcomes, including risk of obesity. Less is known about how discrimination is associated with intermediate physiological markers of health, such as systemic inflammation. This research examined the association between weight discrimination and C-reactive protein (CRP) and whether it varied by participants’ body mass index (BMI). Methods: Cross-sectional design using data from the Health and Retirement Study. Among participants who were overweight or obese (N 5 7,394), regression analysis was used to test for an association between weight discrimination and CRP and whether this association was moderated by BMI. Similar associations among seven other attributions for discrimination were tested. Results: The association between weight discrimination and CRP varied as a function of BMI: At BMI between the thresholds for overweight and obesity (BMI 25–30), weight discrimination was associated with higher circulating levels of CRP; there was no association between weight discrimination and CRP as BMI approached Class 3 obesity (BMI 40). A similar pattern emerged for discrimination based on a physical disability, but not for the other attributions for discrimination (e.g., race, age). Conclusions: Weight discrimination is associated with higher circulating CRP, an association that is moderated by BMI. Obesity (2014) 22, 1959–1961. doi:10.1002/oby.20789
Introduction It is not uncommon for individuals who are overweight or obese to be discriminated against on the basis of their weight (1). These experiences are not just unpleasant but also have significant health consequences. Individuals who are obese who experience weight discrimination, for example, decline more rapidly in mobility over 10 years (2) and are more likely to remain obese over a four-year follow-up period (3) than individuals who are obese who do not experience such discrimination. Although this growing literature implicates perceived weight discrimination in health outcomes, less research has focused on its association with intermediate physiological markers that may contribute to declines in health. Inflammatory markers, particularly C-reactive protein (CRP), are of great interest due to their role in significant health conditions and links to psychosocial factors. CRP is a marker of systemic inflammation that is an independent predictor of cardiovascular disease and diabetes (4,5). CRP has also been associated with psychological factors, such as the development of depression (6), and social factors, including perceived discrimination. For example, older African Americans who report more experiences with discrimination have
higher levels of CRP (7). Whether this association extends to weight discrimination is not yet known. The present study examines the association between perceived weight discrimination and CRP. Because of its strong association with obesity, we tested whether body mass index (BMI) moderated the association between weight discrimination and this inflammatory marker, in addition to testing for a main effect. Since individuals who are overweight or obese more commonly report weight discrimination than individuals who are more lean, we focus on those with a BMI 25.
Methods Participants Participants were drawn from the Health and Retirement Study (HRS), a longitudinal study of Americans ages 50 and older (8). Starting in 2006, HRS implemented an enhanced face-to-face interview that included a psychosocial questionnaire (9) and biomarker assessment (10). Half of the HRS participants completed this interview in 2006; the other half completed it in 2008; we used the combined 2006 and 2008 assessments for analysis. We selected participants who had BMIs above the threshold for
1
Florida State University College of Medicine, Tallahassee, Florida, USA. Correspondence: Angelina R. Sutin ([email protected]) 2 Department of Sport Sciences, Psychology and Medicine, University of Montpellier, Montpellier, France 3 Department of Psychology, University of Bologna, Bologna, Italy
Funding agency: The Health and Retirement Study is sponsored by the National Institute on Aging (NIA-U01AG009740) and conducted by the University of Michigan. Author contributions: ARS conceived the study and analyzed the data. YS, ML, and AT provided critical feedback and direction. All authors wrote the paper and had final approval of the submitted version. Disclosure: The authors declare no conflict of interest. Additional Supporting Information may be found in the online version of this article. Received: 21 February 2014; Accepted: 29 April 2014; Published online 14 May 2014. doi:10.1002/oby.20789
www.obesityjournal.org
Obesity | VOLUME 22 | NUMBER 9 | SEPTEMBER 2014
1959
Obesity
Discrimination and CRP Sutin et al.
TABLE 1 Linear regression analysis predicting log CRP from
perceived weight discrimination Log CRP Predictor
b
SE
b
Age Age squared Sex Race (Black) Race (Other) Education BMI Weight discrimination BMI 3 weight discrimination
20.01 0.00 0.27 0.21 20.14 20.03 0.29 0.14 20.09
0.01 0.01 0.03 0.04 0.08 0.01 0.02 0.06 0.04
20.01 0.00 0.12b 0.06b 20.02 20.09b 0.25b 0.04ba 20.04b
N57,394. CRP 5 C-reactive protein, BMI 5 body mass index, b 5 unstandardized beta coefficient, SE 5 standard error. a Significant in the fully adjusted model. b P < 0.05
overweight (i.e., 25), completed the questionnaire, and had valid CRP values. A total of 7,394 participants met these criteria (Mage 5 67.23, SD 5 9.74; 57% female; 12% African American; 3% other race).
and their interaction, controlling for age, age squared, sex, ethnicity, and education. Although weight discrimination and BMI were correlated (r 5 0.32), the variance inflation factor was only 1.16, which is well below the 2.50 threshold for concern about multicollinearity. We followed a similar procedure for the other attributions to determine whether this effect was specific to weight discrimination or if there was a more general pattern for attributions for discrimination.
Results A total of 695 participants (9.4%) reported that they had been discriminated against because of their weight. As expected, BMI was a strong predictor of CRP. The association between weight discrimination and CRP was qualified by an interaction with BMI (Table 1). Among participants with relatively lower BMI, having experienced weight discrimination was associated with higher levels of inflammation. Among participants with relatively higher BMI, however, weight discrimination was unrelated to inflammation (Figure 1). This interaction was fairly specific to weight discrimination. With one exception—physical disability—the other attributions for discrimination were unrelated to CRP, and the interactions between each attribution and BMI were not significant (Supporting Information Table 1). Similar to weight discrimination, perceived discrimination based on a physical disability was associated with more inflammation at relatively lower, but not higher, BMI.
Measures Perceived discrimination.
Participants rated their experience of everyday discrimination (11) and attributed those experiences to personal characteristics, including weight (12). Participants could also have attributed those experiences to their ancestry, sex, race, age, physical disability, other aspects of physical appearance, and/or sexual orientation. Although single-item measures are not ideal, they have been used successfully to track trends in weight discrimination (1) and to document the correlates of weight bias (3).
Discussion The present research adds to the growing literature that documents the association between perceived weight discrimination and physical health. Weight discrimination is not only related to significant health outcomes, such as mobility (2) and obesity (3), but also to
High sensitivity C-reactive protein. To obtain a blood sample, the participant’s finger was cleansed with an alcohol swab, pricked with a sterile lancet, and the blood droplets were placed on specially treated filter paper. Blood samples were assayed for CRP at the University of Vermont using a standard ELIZA assay (see ref. 10 for details). Due to the skewed distribution, we took the natural log to normalize the distribution. The correlation between the raw and transformed CRP was 0.68.
Body mass index. Trained staff took anthropometric measurements during the face-to-face interview. Height was measured without shoes and recorded to the nearest quarter inch. Weight was measured without shoes and with light clothing using a Healthometer 830 kiloliter scale (Jarden Corporation, Rye, NY) and recorded to the nearest half pound (up to 330 pounds). BMI was calculated as kg/m2 (M 5 31.43, SD 5 5.04).
Analytic strategy We used Aiken and West’s (13) method for interactions to test whether BMI moderated the association between weight discrimination and inflammation among participants who were overweight and obese. Specifically, we used linear regression to predict logtransformed CRP from weight discrimination, mean-centered BMI,
1960
Obesity | VOLUME 22 | NUMBER 9 | SEPTEMBER 2014
FIGURE 1 Association between perceived weight discrimination and log CRP estimated from the regression equation, plotted at the mean BMI of the sample (Mean BMI 5 31.42, SD 5 5.04) and 1 standard deviation below (BMI 26) and above (BMI 36) the sample mean.
www.obesityjournal.org
Brief Cutting Edge Report
Obesity
EPIDEMIOLOGY/GENETICS
intermediate physiological markers of health. In the present study, individuals who perceived weight discrimination had more systemic inflammation, but this association varied as a function of BMI. Among participants with relatively lower BMI (BMI closer to 30), discrimination was associated with higher CRP, whereas it was unrelated to CRP among participants with relatively higher BMI (BMI closer to 40). There is a strong linear association between obesity and inflammation—as BMI increases, so does CRP—and there may be a point at which higher CRP is due primarily to adiposity. That is, most of the variance may be attributed to BMI, overwhelming the effect of psychological or social factors on inflammation. At relatively lower BMI, however, weight discrimination is associated with higher CRP. The behavioral coping mechanisms associated with perceived weight discrimination may contribute to this association. Individuals who perceive discrimination based on their weight, for example, tend to overeat to cope with the stress and also avoid physical activity (14). Experimental manipulations of stigma also suggest that individuals who are overweight consume more calories following a stigmatizing experience (15). Since diet and physical activity are both associated with inflammation (16,17), these behavioral ways of coping with weight discrimination may contribute to the association with higher inflammation. These coping strategies may also be more specific to weight discrimination than to other forms of discrimination. The present research indicated that the association between weight discrimination and CRP is moderated by BMI; CRP may also be a mediator between weight discrimination and obesity. We have shown previously that perceiving weight discrimination is associated with risk of becoming and remaining obese over four years (3). Since inflammatory markers have been associated prospectively with weight gain among adults (18), higher CRP may be one pathway through which discrimination contributes to the subsequent development and maintenance of obesity. That is, for individuals who are overweight, this higher level of CRP may then contribute to the association between weight discrimination and risk for obesity. The present study documents the moderator part of this pathway; future research needs to test the proposed mediator pathway. With one exception, discrimination based on attributions to other personal characteristics was unrelated to CRP. Similar to weight discrimination, the effect of discrimination based on a physical disability on CRP was only apparent among individuals with relatively lower BMI. In the current research, however, we were unable to control for who had a disability, which may mean that the physical condition associated with the disability may be more strongly associated with CRP than the social experience of discrimination. In addition, it was surprising that attributions for discrimination to the other six characteristics were unrelated to CRP. Given that previous research has found discrimination based on other characteristics to be associated with inflammation (7) and obesity (19), more research is needed before concluding that weight and physical disability are the only attributions for discrimination that are associated with higher inflammation. The present study had several strengths, including a large and fairly diverse sample. There are also limitations that need to be addressed in future research. First, our sample was primarily older adults; this association should be tested in a younger population. Second, the
www.obesityjournal.org
data were cross-sectional; longitudinal data are needed to test the temporal relations between discrimination and inflammation. Third, future research could test the mechanisms hypothesized to contribute to the discrimination–CRP link, such as whether diet and physical activity mediate the association between weight discrimination and CRP. Finally, future research could also test the hypothesis that inflammation contributes to the association between weight discrimination and the development and maintenance of obesity. This research is a step toward identifying physiological mechanisms that link discrimination to physical health. O
Acknowledgements HRS data is publically available at http://hrsonline.isr.umich.edu/. C 2014 The Obesity Society V
References 1. Andreyeva T, Puhl RM, Brownell KD. Changes in perceived weight discrimination among Americans, 1995–1996 through 2004–2006 Obesity 2008;16:1129-1134. 2. Schafer MH, Ferraro KF. The stigma of obesity: Does perceived weight discrimination affect identity and physical health? Soc Psychol Q 2011;74:76-97. 3. Sutin AR, Terracciano A. Perceived weight discrimination and obesity. PLoS One 2013;8:e70048. 4. Danesh J, Wheeler JG, Hirschfield GM, et al. C-reactive protein and other circulating markers of inflammation in the prediction of coronary heart disease. N Engl J Med 2004;350:1387-1397. 5. Pradhan AD, Manson JE, Rifai N, et al. C-reactive protein, interleukin 6, and risk of developing type 2 diabetes mellitus. JAMA 2001;286:327-334. 6. Wium-Andersen MK, Ørsted DD, Nielsen SF, Nordestgaard BG. Elevated Creactive protein levels, psychological distress, and depression in 73,131 individuals. JAMA Psychiatry 2013;70:176-184. 7. Lewis TT, Aiello AE, Leurgans S, Kelly J, Barnes LL. Self-reported experiences of everyday discrimination are associated with elevated C-reactive protein levels in older African-American adults. Brain Behav Immun 2010;24:438-443. 8. Health and Retirement Study, 2006 and 2010 Core public use dataset. Produced and distributed by the University of Michigan with funding from the National Institute on Aging (grant number NIA U01AG009740). Ann Arbor, MI, 2012. 9. Clarke P, Fisher G, House J, Smith J, Weir D. Guide to Content of the HRS Psychosocial Leave-Behind Participant Lifestyle Questionnaires: 2004 & 2006. Ann Arbor, MI: University of Michigan, 2008. 10. Crimmins E, Faul J, Kim JK, et al. Documentation of Biomarkers in the 2006 and 2008 Health and Retirement Study. Ann Arbor, MI: Survey Research Center University of Michigan; 2013. 11. Williams DR, Yu Y, Jackson JS, Anderson NB. Racial differences in physical and mental health. Socio-economic status, stress and discrimination. J Health Psychol 1997;2:335-351. 12. Kessler RC, Mickelson KD, Williams DR. The prevalence, distribution, and mental health correlates of perceived discrimination in the United States. J Health Soc Behav 1999;40:208-230. 13. Aiken LS, West SG. Multiple Regression: Testing and Interpreting Interactions. Thousand Oaks, CA: Sage; 1991. 14. Vartanian LR, Novak SA. Internalized societal attitudes moderate the impact of weight stigma on avoidance of exercise. Obesity 2011;19:757-762. 15. Schvey NA, Puhl RM, Brownell KD. The impact of weight stigma on caloric consumption. Obesity 2011;19:1957-1962. 16. Fung TT, McCullough ML, Newby PK, et al. Diet-quality scores and plasma concentrations of markers of inflammation and endothelial dysfunction. Am J Clin Nutr 2005;82:163-73. 17. Healy GN, Matthews CE, Dunstan DW, Winkler EA, Owen N. Sedentary time and cardio-metabolic biomarkers in US adults: NHANES 2003-06. Eur Heart J 2011; 32:590-597. 18. Duncan BB, Schmidt MI, Chambless LE, Folsom AR, Carpenter M, Heiss G. Fibrinogen, other putative markers of inflammation, and weight gain in middle-aged adults—The ARIC study. Atherosclerosis Risk in Communities. Obes Res 2000;8: 279-286. 19. Cozier YC, Yu J, Coogan PF, Bethea TN, Rosenberg L, Palmer JR. Racism, Segregation, and Risk of Obesity in the Black Women’s Health Study. Am J Epidemiol 2014;179:875-883.
Obesity | VOLUME 22 | NUMBER 9 | SEPTEMBER 2014
1961
