Psychosocial and behavioral correlates of dieting among overweight and non-overweight adolescents

Journal of Adolescent Health 38 (2006) 569 –574

Original article

Psychosocial and behavioral correlates of dieting among overweight and non-overweight adolescents Scott Crow, M.D.a,*, Marla E. Eisenberg, Sc.D., M.P.H.b, Mary Story, Ph.D.c, and Dianne Neumark-Sztainer, Ph.D.a a

Department of Psychiatry, University of Minnesota, Minneapolis, Minnesota Department of Pediatrics, University of Minnesota, Minneapolis, Minnesota c School of Public Health, University of Minnesota, Minneapolis, Minnesota Manuscript received January 5, 2005; manuscript accepted May 6, 2005

b

Abstract:

Purpose: To examine correlates of dieting behavior in overweight and non-overweight youth. Methods: Data came from Project EAT (Eating Among Teens), a study of eating and weightrelated attitudes, behaviors, and psychosocial variables among 4746 adolescents in public schools. Logistic regression was used to compare dieters and non-dieters, and to examine interactions of dieting and overweight status. Results: Approximately one third (31.8%) of the sample was overweight. Dieting in the previous year was reported by 55.2% of girls and 25.9% of boys. Dieting was associated with similarly elevated rates of extreme weight control behaviors, body dissatisfaction, and depression in both the non-overweight and overweight groups for both boys and girls. Girls reporting dieting behavior in both the non-overweight and overweight groups had similarly elevated risk for cigarette use, alcohol use, and marijuana use. Conclusions: The negative correlates of dieting are similarly common among teens of varying weight status. These data suggest that dieting may not be a preferred method of weight management, even for overweight adolescents. Regardless of weight status, dieting may be a marker for other unhealthy behaviors and depressed mood in adolescents. © 2006 Society for Adolescent Medicine. All rights reserved.

Keywords:

Dieting; Adolescents; Overweight; Body dissatisfaction; Depression

Overweight and obesity are highly prevalent in many parts of the world, including the United States [1,2]. This prevalence has risen at a rapid rate among both youth and adults [3,4]. Obesity has received increasing attention of late, triggering increased interest in both the treatment and prevention of obesity among children and adolescents. For both prevention efforts and for treatment, weight loss dieting may be recommended [5]. Dieting is a widely prevalent behavior among adolescents in many countries, but is associated with a wide range

*Address correspondence to: Scott Crow, M.D., Department of Psychiatry, University of Minnesota Medical School, F292/2A West Building, 2450 Riverside Avenue, Minneapolis, MN 55454-1495. E-mail address: [email protected].

of problematic attitudes and behaviors [6 –12]. The use of extreme or unhealthy weight control behaviors is associated with other health risk behaviors [13,14]; the same may be true for typical weight loss dieting [15–21]. Overweight adolescents engage in dieting more often than do nonoverweight adolescents [22–25]; at the same time, dieting also predicts weight gain and obesity onset in longitudinal studies [26,27]. Thus, dieting behavior has been shown to co-occur with a variety of negative correlates in adolescents, and might belong to a cluster of risk behaviors. However, as obesity becomes more common in adolescents, weight loss strategies are in greater and greater need. Perhaps weight loss dieting could be a reasonable, health-promoting behavior among overweight or obese adolescents, while simulta-

1054-139X/06/$ – see front matter © 2006 Society for Adolescent Medicine. All rights reserved. doi:10.1016/j.jadohealth.2005.05.019

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S. Crow et al. / Journal of Adolescent Health 38 (2006) 569 –574

neously carrying health risks for those not overweight and thus not “in need of” dieting. Alternatively, dieting may carry similar risks regardless of weight status. The goal of the current study was to examine correlates of dieting in overweight and non-overweight youth utilizing a large, community sample. Methods The data for this study were drawn from Project EAT (Eating Among Teens). In brief, the Project EAT survey has a 221-question classroom-administered survey assessing nutritional, weight-related, and psychosocial factors developed based on existing instruments, with input from multidisciplinary experts in adolescent health and focus groups with youth. Participants were 4746 students in public high schools and middle schools in the greater Twin Cities area of Minnesota. The overall student response rate was 81.5%. The survey was administered by trained research staff in one 90-minute or two 50-minute class periods. Measured heights and weights were obtained by trained research staff in a private area. Approval was received from the Institutional Review Board and the consent processes were approved by each school district’s research board. Measures Weight status. Height was measured without shoes, and weight was measured in street clothes without heavy outerwear; from these measurements, body mass index (BMI; weight [kg]/height [m2]) was calculated. Because 11% of participants were missing observed height and weight data, self-reported height and weight were substituted in these cases to reduce the missing proportion to 3%, as the selfreported and observed measures were highly correlated (r ⫽ .87, p ⬍ .001). Gender- and age-specific definitions for underweight, normal weight, and overweight were based on growth charts from the Centers for Disease Control and Prevention [28]. For the present study, subjects classified as underweight (BMI ⬍ 15th percentile) or average weight (BMI 15th to ⬍ 85th percentile) were grouped as “nonoverweight,” and those moderately overweight (BMI 85th to ⬍ 95th percentile) or very overweight (BMI ⱖ 95th percentile) were grouped together as “overweight.”

iors: (1) took diet pills, (2) made myself vomit, (3) used laxatives, or (4) used diuretics. Students endorsing the use of one or more of these methods were classified as using EWCBs. Body satisfaction. Body satisfaction was assessed using a previously described 10-item scale [29] assessing satisfaction with separate body parts and characteristics. Responses were summed to create an overall score (range 10 –50, with higher scores indicative of greater body satisfaction). Cronbach’s alpha for the composite score was .93 for boys and .92 for girls. For the present analyses, the lowest quartile was considered to have “body dissatisfaction.” Depressive symptoms. Depressive symptoms were assessed using a seven-item scale including fatigue, sleep disturbance, appetite change, dysthymic mood, hopelessness, feeling tense/nervous, and worry [30]. The response options “not at all,” “somewhat,” or “very much” were coded 1, 2, or 3, respectively, yielding a scale range of 6 –18, with higher values indicating more severe depressed mood. Cronbach’s alpha was .76 for boys and .75 for girls. The top quartile of respondents was considered to have “high depressive symptoms” for the current analyses. Self-esteem. Self-esteem was measured using six items excerpted from the Rosenberg Self-Esteem Scale [31]. The items were scored 1– 4, yielding a composite score of 6 –24; Cronbach’s alpha was .78 for boys and .78 for girls. The lowest quartile of respondents was considered to have low self-esteem for the current analyses. Substance use. Use of alcohol, cigarettes, and marijuana was each assessed with a question asking “How often have you used the following during the past year?” Students responding “never” were classified as non-users; students responding “a few times” or higher frequency were classified as users.

Dieting for weight loss. Dieting for weight loss purposes was assessed using the question, “How often have you gone on a diet during the last year? By diet, we mean changing the way you eat so you can lose weight.” Response options included: “never,” “1– 4 times,” “5–10 times,” “more than 10 times,” and “I am always dieting.” Students endorsing any dieting in the last year were classified as dieters.

Other variables. Demographic variables for the analysis included the following: (1) Race/ethnicity was assessed with one question: “Do you think of yourself as (a) White, (b) Black or African-American, (c) Hispanic or Latino, (d) Asian-American, (e) Hawaiian or Pacific Islander, or (f) American Indian or Native American.” Respondents were grouped either as white or non-white for multivariate analysis. (2) Socioeconomic status (SES) was based on the highest educational level completed by either parent. When this information was missing (n ⫽ 1058), eligibility for public assistance, eligibility for free or reduced cost school meals, and parental employment status were used to estimate five levels of SES [32,33]. (3) School level was defined as middle school (grades 7 and 8) versus high school (grades 9 –12).

Extreme weight control behaviors (EWCB). The prevalence of EWCB was assessed with the question, “Have you done any of the following things in order to lose weight or keep from gaining weight during the past year?” for the following behav-

Statistical analysis. Chi-square test of significance was used to identify differences in the proportion of each dependent variable by overweight status. Multivariate logistic regression was used to calculate the odds of each dependent

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Table 1 Characteristics of the sample Characteristics Weight status Non-overweight Overweight Dieting for weight loss ECWB (present) Body dissatisfaction High depressive symptoms Low self-esteem Tobacco use Alcohol use Marijuana use

Total n ⫽ 4734

Adolescent girls n ⫽ 2357

Adolescent boys n ⫽ 2377

n (%)

n (%)

n (%)

3132 (68.1) 1464 (31.9) 1886 (40.5) 394 (8.5) 1039 (23.2) 1336 (30.0) 650 (14.8) 1396 (31.6) 1701 (38.6) 955 (21.7)

1535 (67.4) 744 (32.6) 1282 (56.2) 287 (12.4) 728 (32.5) 855 (38.4) 429 (19.7) 718 (32.7) 819 (37.4) 417 (19.1)

1597 (68.9) 720 (31.1) 604 (25.9) 107 (4.6) 311 (13.9) 481 (21.6) 220 (10.0) 678 (30.6) 882 (39.9) 538 (24.4)

For weight status, non-overweight ⫽ ⬍ 85 percentile BMI, overweight ⫽ ⬎ 85 percentile BMI.

variable (separately) for dieters compared to non-dieters. Models were stratified by gender and by overweight status, and control for grade level, white race, and SES. Interaction terms were also added to test the interaction of dieting and overweight status, to determine if the associations between dieting and each dependent variable were significantly different for overweight versus non-overweight participants. A significance level of p ⬍ .05 was set for all analyses. SAS version 8.2 was used for all analyses. Results The weight status of the sample and the frequencies of dieting for weight loss, depressive symptoms, EWCB, body dissatisfaction, self-esteem, and substance use are shown in Table 1. The sample was evenly split by gender (2357 girls, 2377 boys) and was ethnically diverse, with 48.5% of the adolescents white, 19.2% Asian-American, and 19.0% African-American. SES was similarly diverse: 50.0% of the sample was middle or upper middle SES, 36.2% low or lower middle SES, and 13.8% high SES. Two thirds of the sample was of high school age. The majority (68.2%) of the sample was classified as non-overweight, with 31.8% over-

weight. Weight loss dieting was common, endorsed by 55.2% of girls and 25.9% of boys. The relationship of health risk behaviors and psychosocial factors to weight status by gender is shown in Table 2. Overweight adolescents were roughly 1.5–3 times as likely as non-overweight adolescents to report dieting, EWCBs, and body dissatisfaction. Rates of depressive symptoms were also modestly elevated in the overweight participants. Low self-esteem and tobacco, alcohol, and marijuana use were not more common in the overweight group, however. Girls engaging in dieting were significantly more likely than non-dieting girls to have EWCB, low self-esteem, body dissatisfaction, high depressive symptoms, and alcohol, tobacco, and marijuana use (Table 3). Similarly, in boys, EWCB, low self-esteem, body dissatisfaction, and high depressive symptoms were more common among boys who diet than those who didn’t. Marijuana use in boys, conversely, was more common among non-dieters than boys who dieted. When dieters and non-dieters were compared using logistic regression, dieters tended to have significantly elevated odds ratios (ORs) for several psychosocial factors and health risk behaviors among both non-overweight and over-

Table 2 Relationship of health risk behaviors and psychosocial factors to weight status by gender Boys

Dieting EWCB Body dissatisfaction Depressive symptoms Low self-esteem Tobacco use Alcohol use Marijuana use

Girls

Non-overweight (%) n ⫽ 1580

Overweight (%) n ⫽ 706

p

Non-overweight (%) n ⫽ 1523

Overweight (%) n ⫽ 738

p

15.4 4.0 8.7 20.3 9.2 30.6 39.4 25.2

48.9 5.9 25.2 24.5 11.1 30.9 41.4 22.6

⬍ .001 .038 ⬍ .001 .027 .156 .890 .382 .194

46.4 9.8 24.8 36.6 18.2 32.6 38.6 18.7

71.4 17.5 46.5 41.2 21.3 33.1 34.7 19.2

⬍ .001 ⬍ .001 ⬍ .001 .039 .086 .666 .103 .778

EWCB ⫽ Extreme weight control behaviors.

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Table 3 Relationship of health risk behaviors and psychosocial factors to dieting status by gender Boys

EWCB Body dissatisfaction Depressive symptoms Low self-esteem Tobacco use Alcohol use Marijuana use

Girls

Non-dieters (%) n ⫽ 1697

Dieters (%) n ⫽ 589

p

Non-dieters (%) n ⫽ 1027

Dieters (%) n ⫽ 1234

p

2.20 8.6 19.0 7.3 31.5 40.9 25.8

11.6 29.0 29.5 18.0 28.5 37.1 20.4

⬍ .001 ⬍ .001 ⬍ .001 ⬍ .001 .183 .109 .001

2.9 14.7 27.7 10.4 24.9 31.1 16.0

20.1 46.8 47.1 27.0 38.9 42.55 21.6

⬍ .001 ⬍ .001 ⬍ .001 ⬍ .001 ⬍ .001 ⬍ .001 ⬍ .001

EWCB ⫽ Extreme weight control behaviors.

weight participants (Table 4). Girls who reported dieting had elevated ORs for EWCB, low self-esteem, body dissatisfaction, and depressive symptoms, plus tobacco use and alcohol use. For boys, these included EWCB, low selfesteem, body dissatisfaction, and depressive symptoms. These relationships appeared strongest for EWCB; for example, with ORs of 9.31 for non-overweight girls, and 6.82 for overweight girls. For the other variables where elevations were seen, ORs generally ranged between 1.5–3.5 for both boys and girls. Interaction models suggest that the increased risks associated with dieting were similar for overweight and nonoverweight participants. Observed ORs did not differ significantly between non-overweight and overweight boys, or between non-overweight and overweight girls, except for body dissatisfaction in non-overweight (OR ⫽ 5.26) versus overweight girls (OR ⫽ 3.19). Thus, the odds of having a higher degree of body dissatisfaction were significantly greater for non-overweight dieters than overweight dieters. Discussion While dieting has been suggested to be detrimental for teens of healthy weight but beneficial for those who are

overweight [34], findings from the present study show that the risks associated with dieting appear similar for overweight and non-overweight teens. The psychosocial and behavioral risks of dieting, therefore, may outweigh the potential benefits, even for overweight teens. The current study is relatively unique in examining the interaction of weight status and dieting status with regard to health risk behaviors. Notably, this association with adverse health behaviors was independent of weight status. In other words, the attendant health risks of dieting appear to be similar for youth at relatively low and relatively high BMIs. The finding that dieting tends to co-occur with a number of health risk behaviors and measures of diminished emotional well-being regardless of weight status has substantial public health significance. Overweight and obesity are increasingly prevalent among adolescents, and many treatment and prevention strategies are being developed. These span the gamut from primary prevention efforts such as changing exercise patterns and food intake or providing weight report cards to a variety of obesity treatment strategies. Many of these interventions include some degree of diet change for weight loss. An important question certainly exists as to whether these are effective, but independent of that question, these data suggest that such dieting efforts are

Table 4 Odds ratio (OR) for dieters versus non-dieters by weight status and gender* Boys

EWCB Body dissatisfaction Depressive symptoms Low self-esteem Tobacco use Alcohol use Marijuana

Girls

Non-overweight OR (CI)

Overweight OR (CI)

Non-overweight OR (CI)

Overweight OR (CI)

6.28 (3.61–10.95)a 2.44 (1.58–3.75)* 1.68 (1.20–2.35)* 2.11 (1.37–3.24)* 1.02 (.73–1.41) .98 (.72–1.35) .87 (.60–1.25)

3.75 (1.74–8.06)a 3.64 (2.45–5.42)* 1.65 (1.14–2.40)* 2.92 (1.68–5.07)* .90 (.63–1.27) .91 (.66–1.27) .87 (.59–1.28)

9.31 (5.53–15.67)a 5.26 (3.98–6.94)* 2.43 (1.94–3.04)* 3.24 (2.41–4.37)* 1.89 (1.50–2.38)* 1.70 (1.35–2.13)* 1.23 (.93–1.62)

6.82 (3.26–14.26)a 3.19 (2.21–4.62)* 1.76 (1.23–2.52)* 2.82 (1.67–4.75)* 1.75 (1.18–2.59)* 1.60 (1.09–2.35)* 1.54 (.95–2.48)

EWCB ⫽ Extreme weight control behaviors. CI ⫽ 95% confidence interval. a Controlling for grade level, white race, and SES. * p ⬍ .05.

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associated with higher rates of health risk behaviors and poorer emotional adjustment even in adolescents who are overweight. As such, recommendations for dieting as a weight-control measure may need to be reconsidered and perhaps eliminated, particularly if the results of this study are replicated among adolescents engaging in supervised dieting for weight loss. This study replicates work showing that a variety of adverse psychosocial factors, including unhealthy weight control behaviors, low self-esteem, body dissatisfaction, and depressive symptoms were more common in overweight than non-overweight teens [35]. Previous studies have also shown dieting to be a more common behavior among overweight than non-overweight adolescents [22– 24]. Others have reported higher rates of health risk behaviors including smoking among adolescents who diet [15– 19,36 –38]. There are several strengths to the current study, including the large, ethnically and socioeconomically diverse population and relatively high participation rate. One limitation is the cross-sectional nature of the study design. Thus, one cannot conclude with certainty that dieting causes the adverse factors that were found to co-occur with it. A second limitation is that information about the nature and duration of dieting attempts was limited. The dieting behaviors these adolescents engaged in might differ from supervised weight loss programs in nature, adverse correlates, and perhaps effectiveness. There is evidence to suggest that differing intensities of dieting have different correlations with other health-related behaviors [14,15]. Similarly, motivations for dieting behavior were not assessed. It remains possible that the health correlates of dieting to obtain a thin ideal body shape might differ from the correlates of dieting to avoid medical problems. A final limitation is that 11% of subjects had self-report rather than interview, data for height and weight. However, in this data set, correlations of self-report and measured health and weight have ranged from .800 to .964 [39]. The analyses were repeated excluding subjects with self-report data for BMI, and the results did not change. These findings have several implications for future research. First, the relationships observed here are crosssectional and should be examined using prospective designs. Second, more intensive assessment of dieting activities is indicated to attempt to clarify whether some carefully planned dieting behaviors might be beneficial and not be associated with adverse correlates. The adverse correlates of dieting identified here might not extend to supervised weight loss settings. These findings also have policy implications. They suggest that obesity treatment and prevention efforts aimed at adolescents might well benefit from de-emphasizing dieting behaviors. Also, although dieting was much more common in overweight than non-overweight youth, dieting for weight loss was reported by approximately 30% of non-

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overweight youth. This figure underscores the importance of addressing current societal beliefs regarding the value of thinness that appear to put adolescents at risk for the development of disordered eating. Acknowledgments This word was supported in part by grant MCJ-270834 (D. Neumark-Sztainer, principal investigator) from the Bureau of Maternal and Child Health (Title V, Social Security Act), Health Resources and Services Administration, Department of Health and Human Services, US Public Health Service; and grant K-02 MH65919 (SJC). References [1] Mokdad AH, Ford ES, Bowman BA, et al. Prevalence of obesity, diabetes, and obesity-related health factors, 2001. JAMA 2003;289: 76 –9. [2] Flegal KM, Carroll MD, Ogden ?? Cl, et al. Prevalence and trends in obesity among U.S. Adults, 1999 –2000. JAMA 2002;288:1723–7. [3] Ogden CL, Flegal KM, Carroll MD, et al. Prevalence and trends in overweight among U.S. children and adolescents, 1999 –2000. JAMA 2002;288:1728 –32. [4] Hedley AA, Ogden CL, Johnson CL, et al. Prevalence of overweight and obesity among U.S. children, adolescents and adults, 1999 –2002. JAMA 2004;291:2847–50. [5] Clinical Guidelines on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults. Rockville, MD: National Institutes of Health Publication No. 98-4083, September 1998. [6] Brugman E, Meulmeester JF, Spee-van der Wekke A, et al. Dieting, weight and health in adolescents in the Netherlands. Int J Obesity 1997;21:54 – 60. [7] Story M, French SA, Neumark-Sztainer D, et al. Psychosocial and behavioral correlates of dieting and purging in Native American adolescents. Pediatrics 1997;99:1– 8. [8] Calderon LL, Yu CK, Jambazian P. Dieting practices in high school students. J Am Dietetic Assoc 2004;104:1369 –74. [9] Borresen R, Rosenvinge JH. Body dissatisfaction and dieting in 4,952 Norwegian children aged 11–15 years: Less evidence for gender and age differences. Eating Weight Disord 2003;8:238 – 41. [10] Neumark-Sztainer D, Hannan PJ. Weight-related behaviors among adolescent girls and boys. Arch Pediatr Adolesc Med 2000;154:569 – 77. [11] Edlund B, Sjoden PO, Gebre-Medhin M. Anthropometry, body composition and body image in dieting and non-dieting 8 –16-year-old Swedish girls. Acta Paediatr 1999;88:537– 44. [12] Patton GC, Carlin JB, Shao Q, et al. Adolescent dieting: Healthy weight control or borderline eating disorder? J Child Psychol Psychiatry 1997;38:299 –306. [13] Neumark-Sztainer D, Story M, French SA. Covariations of unhealthy weight loss behaviors and other high-risk behaviors among adolescents. Arch Pediatr Adolesc Med 1996;150:304 – 8. [14] Neumark-Sztainer D, Story M, Dixon LB, et al. Adolescents engaging in unhealthy weight control behaviors: Are they at risk for other health-compromising behaviors? Am J Public Health 1998;88:952–5. [15] Rafiroiu AC, Sargent RG, Parra-Medina D, et al. Covariations of adolescent weight-control, health-risk and health-promoting behaviors. Am J Health Behav 2003;27:3–14. [16] French SA, Perry CL, Leon GR, et al. Weight concerns, dieting behavior, and smoking initiation among adolescents: A prospective study. Am J Public Health 1994;84:1818 –20.

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