The prevalence of obesity in the United States has more than doubled in the past three decades.1 More than half of reproductive-age women between 20 and 39 years of age are currently overweight or obese, with African Americans and Hispanics at even higher risk.2 The World Health Organization labeled obesity as the most blatantly visible but most neglected public health problem worldwide.3
Self-perception of body weight is the degree of concordance between perceived and measured weight. Accurate perception of body weight is important for the success of obesity prevention programs. Furthermore, behavioral intervention programs of any kind are not successful unless an overweight person recognizes that he or she is overweight.4–6 Earlier studies have shown that the accuracy in weight perception has been associated with age, sex, race or ethnicity, body mass index (BMI, calculated as weight (kg)/[height (m)]2), income, education, and lifestyle behaviors.5–12 However, data are lacking on reproductive-age women and the association of their weight perception with healthy and unhealthy weight-related behaviors.
Determining the extent of misperception of body weight is especially important in reproductive-age women because they are more likely to be obese than similarly aged men.13 More than one half of reproductive-age women in the United States currently have BMIs more than 25,14 placing them at increased risk for type 2 diabetes mellitus and cardiovascular disease at a young age. Minority women are at even higher risk; an alarming 82% of African-American and 75% of Mexican-American women now meet the criteria for being overweight or obese. Moreover, reproductive-age women are prone to gain excess body weight during pregnancy and postpartum period.15–18 Greater misperception of body weight in this group means less weight loss behavior, which may make them more vulnerable to cardiovascular disease risk factors and other obesity-related diseases. Furthermore, it has not been determined to what extent reproductive-age women are practicing unhealthy weight-related behaviors because of misperception of their body weight. The purpose of this study was to examine misperception of body weight and its association with healthy and unhealthy weight-related behaviors in a multiethnic, reproductive-age population of women.
PARTICIPANTS AND METHODS
We conducted a cross-sectional survey on health behaviors among women 16 to 25 years of age attending one of five publicly funded reproductive health clinics between August 2008 and March 2010. Surveys were self-administered and those who agreed to participate were reimbursed $5 for their time. To assure that patients completed the survey only once during this 2-year interval, study personnel maintained a cumulative database containing the names of those who had previously completed the survey and compared it daily to the names of those appointed for a visit. Women who had previously completed the survey were not approached a second time. All procedures were approved by the Institutional Review Board of the University of Texas Medical Branch.
This study focused on survey questions pertaining to sociodemographic variables, height, weight, weight perceptions, and weight-related behaviors among participants 18 to 25 years old. Age was calculated using years and months. Race and ethnicity were self-reported, with choices including non-Hispanic white, non-Hispanic African American, Hispanic, Asian, Native American or Alaskan native, native Hawaiian or other Pacific Islander, and other. No classification was available for mixed race. We restricted our analysis in this article to non-Hispanic white, non-Hispanic African-American, and Hispanic women because of the limited sample size of other categories. Information about education level, marital status, work hours per week, and Internet use were also obtained by self-report. Height and weight values were obtained from anthropomorphic data recorded in the medical chart. Women with BMIs less than 25 and 25 or more were considered as being normal weight and overweight, respectively. Self-perception of weight was measured by asking, “How would you describe your weight?” Response options included, “very underweight,” “slightly underweight,” “about the right weight,” “slightly overweight,” and “very overweight.” For analysis purposes, these five response options were collapsed into two categories: 1) overweight (includes slightly overweight and very overweight) and 2) normal weight (includes very underweight, slightly underweight, and approximately the right weight). Using their calculated BMI and self-perception of weight, overweight and normal-weight women were then divided into four categories: overweight misperceivers (overweight women who described themselves as underweight or normal weight), overweight actual perceivers (overweight women who described themselves as overweight), normal-weight misperceivers (normal-weight women who described themselves as overweight), and normal-weight actual perceivers (normal-weight women who described themselves as normal weight or underweight).
Eight questions were used to assess behaviors in the previous 30 days engaged in losing weight or keeping from gaining weight. Behaviors assessed (yes or no) included using diet pills, diet powder, or diet liquids, laxatives, diuretics, induced vomiting, skipping meals, eating less or differently, smoking more cigarettes, and not eating carbohydrates. Respondents were also asked about number of days they exercised or played sports for at least 30 minutes continuously in the past week.
Univariable comparisons were performed to compare the two groups (accurate perceivers compared with misperceivers in normal-weight and overweight women) using the χ2 or Student t test, as appropriate. Multivariable logistic regression was used to identify correlates of overweight misperceivers and normal-weight misperceivers. Variables were screened for inclusion in an initial multivariable model. Candidate variables with P≤.20 were included in the initial multivariable model. Multivariable logistic regression was also used to compare weight-related behaviors of misperceivers with accurate perceivers, adjusting for age, race or ethnicity, and BMI. All analyses were performed using STATA 11.
Of the 2,224 women (18–25 years old) included in this study, 48.3% (n=1,076) were Hispanic (primarily Mexican or Mexican American), 27.0% (n=601) were white, 23.8% (n=529) were African American, and 0.8% (n=18) were from other racial or ethnic groups. The mean age of the sample was 21.4 years (standard deviation 2.1; range 18–25 years). Overall, 47.8% (1,062/2,224) of the women had normal weight (BMI less than 25), whereas 52.2% (1,162/2,224) were overweight or obese (BMI 25 or more). Tabulating self-perception of weight with actual weight status showed that 16% (170/1,062) of normal-weight women and 23.0% (267/1,162) of overweight (36.8% of overweight and 10.5% of obese) women were misperceivers (Table 1).
Univariable analyses showed that the mean age was the same for overweight misperceivers and overweight accurate perceivers, but normal-weight misperceivers were slightly older than normal-weight accurate perceivers (Table 2). The mean BMI of overweight accurate perceivers and normal-weight misperceivers was significantly higher than that of their counterparts. Significantly more Hispanic (24.7%) and African-American (28.2%) women were overweight misperceivers compared with white respondents (14.8%), whereas significantly more white (16.0%) and Hispanic women (19.7%) were normal-weight misperceivers compared with African-American women (7.4%). Women who were Internet users, who had some college education, or those who were employed more than 20 hours per week were less likely to be overweight misperceivers. Four correlates (BMI, race or ethnicity, education, and Internet use) that were significant in the univariable analysis remained significant in multivariable logistic regression model, whereas age and hours worked were not (Table 3).
Univariable analyses between self-perception of body weight and weight-related behaviors showed that the overweight misperceivers were significantly less likely to report most of the healthy and unhealthy weight-related behaviors than the overweight accurate perceivers (Table 4). However, the opposite scenario was observed for normal-weight accurate perceivers. The multivariable logistic regression model, after adjusting for age, race, ethnicity, and BMI, showed a similar pattern (Table 5). Overweight misperceivers had significantly lower odds of dieting, skipping meals, and using diet pills, powders, or liquids compared with their counterparts. However, normal-weight misperceivers were significantly more likely than normal-weight accurate perceivers to report both healthy and unhealthy weight-related behaviors. They were more than twice as likely to diet, skip meals, and smoke more cigarettes when compared with normal-weight accurate perceivers. The respective odds were nearly four and five times higher with regard to using diet pills, powder, liquids, and using diuretics.
We performed separate analysis for underweight women. One hundred twenty-five women had BMIs less than 18.5; 65 (52.0%) considered themselves as underweight, 57 (45.6%) considered themselves normal weight, and three (2.4%) considered themselves overweight. Fourteen (11.2%) of the underweight women had a history of using any of the unhealthy behaviors to lose weight or to keep from gaining weight during past 30 days. Eight women considered themselves underweight, whereas six considered themselves normal weight.
We observed that a large number (23%) of overweight and normal-weight (16%) reproductive-age women do not accurately perceive their BMI category. Our finding that nearly one in four overweight reproductive-age women misperceives that her body weight is consistent with those of other population-based large studies that have examined this among adult women.5,7 Furthermore, our observations that underassessment of body weight was more common in African Americans and in women with lower education levels and overassessment of body weight was more common in white and Hispanic women and both are consistent with other published reports.5–7 Together, these studies provide evidence that misperception of body weight is common in adult women. This report adds to the literature the observation that among reproductive-aged women, both overweight accurate perceivers and normal-weight misperceivers frequently participate in both healthy and unhealthy weight-related behaviors.
Underassessment of body weight is common among adolescent and adult men and women.5–8,10–12,19,20 Because reproductive-aged women are more susceptible to gain weight than similar-aged men, interventional programs should emphasize the consequences of underassessment of body weight and health risk associated with excess body weight. Overassessment of body weight is also common and well-documented.5 One notable finding in this study is that reproductive-age women, normal-weight misperceivers had significantly higher odds of reporting several unhealthy weight-related behaviors (eg, using diet pills, liquids, or powders; using diuretics; and smoking more cigarettes), which is a real concern. These behaviors have been found to be associated with adverse physical, psychological, and nutritional outcomes and eating disorders.21–27 Weight gain over time, increase in depressive symptoms, inadequate nutritional intake, bulimia, and anorexia were reported to be higher in individuals with unhealthy weight-related behaviors. This finding may give clinicians a point of discussion when counseling reproductive-age women about obesity and weight loss issues. As a prevention program, clinicians should routinely inquire about unhealthy weight-related behaviors and counsel them appropriately.
Weight misperception is a threat to the success of the obesity prevention program. The Health Belief Model offers some potential explanation for the mechanisms underlying self-perception and behavior change to avoid obesity. The model is based on six components: perceived susceptibility, perceived severity, perceived benefits, perceived barriers, cues to action, and self-efficacy. The first component is related to weight perception. If overweight individuals do not perceive that they are overweight, then other components of the Health Belief Model would not work for them. In an earlier study in reproductive-age women, we observed that even perceived weight gain was not enough to increase weight loss behavior.28 It could be attributable to the fact that even after weight gain, they do not assume themselves as overweight. Thus, the first prerequisite of the success of obesity prevention program is that the target group needs to recognize themselves as overweight. Addressing misperception should be the first step for the obesity prevention ladder.
Our finding that weight misperception is a determinant of healthy and unhealthy weight-related behaviors has several implications. First, the lower likelihood of overweight misperceivers to practice healthy weight loss behavior than overweight accurate perceivers seems to have a negative effect on an obesity prevention program. Second, the higher likelihood of normal-weight misperceivers to practice four of the six unhealthy weight loss behaviors is a matter of concern. More than one third of normal-weight misperceivers had at least one unhealthy weight-related behavior, and this is a public health threat because these behaviors have medical and psychological consequences.21–27 This double-edged problem of weight misperception needs to be addressed by appropriate awareness programs from health care providers and from the media.
The strength of our study includes use of actual height and weight to calculate BMI-based weight status; several studies have observed that BMI based on self-reported height and weight are underestimated.29,30 This study has several limitations. We examined misperception of weight in women 18 to 25 years old, so we do not know whether similar findings would be observed in older reproductive-age women. In addition, we used BMI to categorize overweight and normal weight. Because BMI does not distinguish between lean mass and fat mass, we may have misclassified some women who were more muscular.
In conclusion, we observed that misperception of weight and unhealthy weight-related behaviors are common in reproductive-age women. Clinicians should provide patient-specific counseling to reproductive-age women based on the presence of misperception of weight and unhealthy weight-related behaviors. Efforts to educate them about accurate weight status and safe and effective weight loss strategies are essential. Obesity-related consequences of misperception and dangers of unhealthy weight-related practices should be highlighted specifically.
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© 2010 by The American College of Obstetricians and Gynecologists. Published by Wolters Kluwer Health, Inc. All rights reserved.
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