7
Research Article Body Mass Index and Weight Loss in Overweight and Obese Korean Women: The Mediating Role of Body Weight Perception Sunjoo Boo, RN, PhD * College of Nursing, Gachon University, Yeonsu-gu, Incheon, South Korea article info Article history: Received 24 February 2013 Received in revised form 22 July 2013 Accepted 2 September 2013 Keywords: Korean obesity weight loss weight perception women summary Purpose: This study were to assess the relationships among BMI, body weight perception, and efforts to lose weight in a public sample of Korean women who are overweight and obese and to examine the mediating role of body weight perception on the relationship between BMI and weight loss efforts. Methods: This cross-sectional study used data from the 2008 Korea National Health and Nutrition Examination Survey. The sample was 1,739 Korean women 20 years old or older with body mass index (BMI) 23 kg/m 2 . Bivariate relationships among variables of interests were assessed. Three separate regressions were used to test the mediating role of body weight perception on the relationship between BMI and weight loss efforts. Results: BMI and body weight perception were signicant correlates of weight loss efforts. BMI was signicantly associated with weight perception, but a large proportion of women underestimated their weight. Weight perception partially mediated the relationship between BMI and weight loss efforts in Korean women. Conclusion: In light of the high prevalence of overweight or obesity and the many health consequences associated with obesity, Korean women should be aware of a healthy body weight and try to achieve that weight. Nursing interventions should consider body weight perception to effectively motivate over- weight and obese Korean women to lose weight, as necessary. Copyright Ó 2013, Korean Society of Nursing Science. Published by Elsevier. All rights reserved. Introduction Over the past several decades, Korea has experienced rapid economic growth, resulting in unhealthy changes in lifestyle and diet that have led to signicant increases in obesity (Yoon et al., 2006). A recently published study using nationally representative data showed that one in two Korean women aged 20 or older is overweight or obese, while more than 60% of women aged 50 or older are considered overweight or obese (Boo & Froelicher, 2012a). Excess weight is a risk factor for numerous chronic conditions, including diabetes mellitus and cardiovascular disease (Must et al., 1999). Weight loss can favorably reduce the risk for such diseases (Hamman et al., 2006; Pi-Sunyer et al., 2007). Therefore, over- weight or obese individuals need to be counseled and encouraged to embark on efforts to lose weight. Research has shown that trying to lose weight is related to the level of overweight (Andreyeva, Long, Henderson, & Grode, 2010; Bersamin, Hanni, & Winkleby, 2010; Bish et al., 2005; Koo & Park, 2011), but not everyone who is overweight or obese tries to lose weight (Andreyeva et al.; Bersamin et al.; Bish et al.; Koo & Park). A study by Koo and Park showed that only 23.5% of overweight and 17.2% of obese middle-aged Korean women are trying to control weight. This may be an indicator of a low level of readiness for weight loss in overweight or obese individuals. Thus, an important opportunity exists for the success of weight loss interventions. Sociodemographic factors such as age, race, education level, in- come, and smoking status are also related to trying to lose weight (Anderson, Eyler, Galuska, Brown, & Brownson, 2002; Bersamin et al.; Bish et al.; Lee et al., 2005). Although these factors are useful in deciding where to direct weight loss interventions, they may not be helpful in designing more effective or appropriate weight loss interventions. A better understanding about what motivates over- weight or obese individuals to try to lose weight might help in designing more effective weight loss interventions. Motivation for weight loss in women can include body weight perception, which is the subjective evaluation of ones body weight and is related to weight loss concerns or health behaviors (Clarke, 2002; Putterman & Linden, 2004). Studies from the United States have demonstrated that dissatisfaction with weight is a strong * Correspondence to: Sunjoo Boo, RN, PhD, College of Nursing, Gachon University, 191 Hambakmoero, Yeonsu-gu, Incheon, 406-799, South Korea. E-mail address: [email protected] Contents lists available at ScienceDirect Asian Nursing Research journal homepage: www.asian-nursingresearch.com 1976-1317/$ e see front matter Copyright Ó 2013, Korean Society of Nursing Science. Published by Elsevier. All rights reserved. http://dx.doi.org/10.1016/j.anr.2013.09.003 Asian Nursing Research 7 (2013) 191e197

Body Mass Index and Weight Loss in Overweight and Obese Korean.pdf

Embed Size (px)

Citation preview

Page 1: Body Mass Index and Weight Loss in Overweight and Obese Korean.pdf

lable at ScienceDirect

Asian Nursing Research 7 (2013) 191e197

Contents lists avai

Asian Nursing Research

journal homepage: www.asian-nursingresearch.com

Research Article

Body Mass Index and Weight Loss in Overweight and Obese KoreanWomen: The Mediating Role of Body Weight Perception

Sunjoo Boo, RN, PhD *

College of Nursing, Gachon University, Yeonsu-gu, Incheon, South Korea

a r t i c l e i n f o

Article history:Received 24 February 2013Received in revised form22 July 2013Accepted 2 September 2013

Keywords:Koreanobesityweight lossweight perceptionwomen

* Correspondence to: Sunjoo Boo, RN, PhD, College o191 Hambakmoero, Yeonsu-gu, Incheon, 406-799, So

E-mail address: [email protected]

1976-1317/$ e see front matter Copyright � 2013, Kohttp://dx.doi.org/10.1016/j.anr.2013.09.003

s u m m a r y

Purpose: This study were to assess the relationships among BMI, body weight perception, and efforts tolose weight in a public sample of Korean women who are overweight and obese and to examine themediating role of body weight perception on the relationship between BMI and weight loss efforts.Methods: This cross-sectional study used data from the 2008 Korea National Health and NutritionExamination Survey. The sample was 1,739 Korean women 20 years old or older with body mass index(BMI) � 23 kg/m2. Bivariate relationships among variables of interests were assessed. Three separateregressions were used to test the mediating role of body weight perception on the relationship betweenBMI and weight loss efforts.Results: BMI and body weight perception were significant correlates of weight loss efforts. BMI wassignificantly associated with weight perception, but a large proportion of women underestimated theirweight. Weight perception partially mediated the relationship between BMI and weight loss efforts inKorean women.Conclusion: In light of the high prevalence of overweight or obesity and the many health consequencesassociated with obesity, Korean women should be aware of a healthy body weight and try to achieve thatweight. Nursing interventions should consider body weight perception to effectively motivate over-weight and obese Korean women to lose weight, as necessary.

Copyright � 2013, Korean Society of Nursing Science. Published by Elsevier. All rights reserved.

Introduction

Over the past several decades, Korea has experienced rapideconomic growth, resulting in unhealthy changes in lifestyle anddiet that have led to significant increases in obesity (Yoon et al.,2006). A recently published study using nationally representativedata showed that one in two Korean women aged 20 or older isoverweight or obese, while more than 60% of women aged 50 orolder are considered overweight or obese (Boo & Froelicher, 2012a).Excess weight is a risk factor for numerous chronic conditions,including diabetes mellitus and cardiovascular disease (Must et al.,1999). Weight loss can favorably reduce the risk for such diseases(Hamman et al., 2006; Pi-Sunyer et al., 2007). Therefore, over-weight or obese individuals need to be counseled and encouragedto embark on efforts to lose weight.

Research has shown that trying to lose weight is related to thelevel of overweight (Andreyeva, Long, Henderson, & Grode, 2010;

f Nursing, Gachon University,uth Korea.

rean Society of Nursing Science. P

Bersamin, Hanni, & Winkleby, 2010; Bish et al., 2005; Koo & Park,2011), but not everyone who is overweight or obese tries to loseweight (Andreyeva et al.; Bersamin et al.; Bish et al.; Koo & Park). Astudy by Koo and Park showed that only 23.5% of overweight and17.2% of obese middle-aged Korean women are trying to controlweight. This may be an indicator of a low level of readiness forweight loss in overweight or obese individuals. Thus, an importantopportunity exists for the success of weight loss interventions.Sociodemographic factors such as age, race, education level, in-come, and smoking status are also related to trying to lose weight(Anderson, Eyler, Galuska, Brown, & Brownson, 2002; Bersaminet al.; Bish et al.; Lee et al., 2005). Although these factors are usefulin deciding where to direct weight loss interventions, they may notbe helpful in designing more effective or appropriate weight lossinterventions. A better understanding about what motivates over-weight or obese individuals to try to lose weight might help indesigning more effective weight loss interventions.

Motivation for weight loss in women can include body weightperception, which is the subjective evaluation of one’s body weightand is related to weight loss concerns or health behaviors (Clarke,2002; Putterman & Linden, 2004). Studies from the United Stateshave demonstrated that dissatisfaction with weight is a strong

ublished by Elsevier. All rights reserved.

Page 2: Body Mass Index and Weight Loss in Overweight and Obese Korean.pdf

S. Boo / Asian Nursing Research 7 (2013) 191e197192

predictor of trying to lose weight in women (Anderson et al., 2002;Lemon, Rosal, Zapka, Borg, & Andersen; 2009). Other studies havefound complex relationships among bodymass index (BMI), weightperception, and weight loss efforts in African Americans (Lee et al.,2005; Wang, Liang, & Chen, 2009). It has been suggested that asso-ciations between BMI and weight loss efforts may be mediated bybodyweight perception (Lee et al.). If such effects exist in the generalpopulation of Koreanwomenwho are overweight or obese, we canenhance our understanding of the complex relationships amongactual weight, weight perception, and weight loss efforts. Thefindingwill also provide insights in designingmore effectiveweightloss interventions for Koreanwomenwho are overweight or obese.

However, most previous studies about bodyweight perception inKorea have generally focused on adolescents or college students invery narrow geographic areas or have examined issues related toeating disorders (Kim, 2012; Kim, Kim, Cho, & Cho, 2008; Lee & Oh,2004). Relatively little is known about perceived body weight inadult Korean women who are overweight or obese in terms of BMIand trying to lose weight. Previous studies only bivariately analyzedthe relationships among them (Kim, Jeong, Kim, & Park, 2004; Koo &Park, 2011). In addition, body weight perception is likely to beinfluenced by cultural factors so that the evidence from Westerncountries may not be appropriate for Koreans. Therefore, the pur-poses of this study are to systematically assess the relationshipsamongBMI,weightperception, andweight loss efforts in a nationallyrepresentative sample of Korean women who are overweight orobese and to examine the plausibility of themediating effect of bodyweight perception on the relationship between level of obesity andweight loss efforts. Figure 1 shows the conceptual framework of thisstudy. It is hypothesized that (a)womenwhoare overweightorobesearemore likely to try losingweight, and (b) excess bodyweight leadsto self-perceived overweight or obesity, which (c) in turn results inthe efforts to lose weight (This study does not aim to evaluate theimpact of the covariates).

Methods

Study design

This is a cross-sectional secondary data analysis. Data from the2008 Korea National Health and Nutrition Examination Survey IV(KNHANES IV) by the Korea Centers for Disease Control and Pre-vention (KCDC) were used. KNHANES IV used a stratified, multi-stage probability sampling design. Details of the sampling designand survey procedures of the original study are provided elsewhere(Boo & Froelicher, 2012a, 2012b).

Body weight perception

Covariates such as sociodemographic factors

Weight-loss efforts Body weight status (Based on BMI) (A)

(B) (C)

Figure 1. Conceptual framework: Relationship among body weight, body weightperception, and weight-loss efforts. Note. BMI ¼ body mass index. This study does notdiscuss the impact of the covariates.

Setting and sample

The sample for this study was limited to womenwho were aged20 or older, completed the survey, and were overweight or obese(BMI � 23 kg/m2). Women who were pregnant or breast-feedingwere excluded because pregnancy or lactation may influence BMIand weight control behavior. Of the 5,374 women participants inthe original KNHANES IV survey, 3,814 women were aged 20 orolder and completed the survey. Among them, 1,879 women had aBMI greater than 23 kg/m2; 33 of these women were pregnant and22 women were breast-feeding. Thus, 1,824 women were eligiblefor the analysis of this study. Among them, those with missing dataon demographic characteristics (n ¼ 77), on body weight percep-tion (n ¼ 7), and on whether they were trying to lose weight or not(n ¼ 1) were excluded, yielding a final sample of 1,739 women forthe analysis of this study.

Ethical consideration

The original survey, KNHANES IV, was approved by the KCDCInstitutional Review Board. Informed consent was obtained fromeach KNHANES participant. This study used only de-identifiedexisting data with no subject contact. The SPSS data set and thedata directory were downloaded directly from the KCDC website(http://knhanes.cdc.go.kr/); the downloaded electronic data wereprotected with a password.

Data collection and measurements

Face-to-face interviews and physical examinations were per-formed in a mobile examination center or in public health centers.Variables were defined as follows:

Overweight and obesity

Overweight and obesity are based on BMI. BMI, defined asweight in kilograms divided by height in meters squared (kg/m2),was calculated using measured height and weight. Overweight andobesity in this study were defined as 23 kg/m2 � BMI < 25 kg/m2

and BMI� 25 kg/m2, respectively, based on the Asian-Pacific regionof the World Health Organization (WHO) data (WHO, 2000).

Body weight perception

Weight perception was assessed using responses to thefollowing survey question: Do you consider yourself now to be veryunderweight, slightly underweight, about the right weight, over-weight, or obese? Because few women reported themselves to bevery underweight, those who reported themselves as very under-weight or slightly underweight were collapsed into a single cate-gory for this study. Thus, the variable used in the analyses of thisstudy included four categories: underweight, about right, over-weight, and obese.

Weight loss efforts

Attempts to lose weight were assessed with the followingquestion: During the past 12 months, what have you been trying todo about your body weight? Response choices were “gain weight”,“lose weight”, “stay the same”, and “nothing”. These responseswere dichotomized for this study: Womenwho answered that theywere trying to lose any amount of weight were identified as thosetrying to lose weight (yes/no).

Page 3: Body Mass Index and Weight Loss in Overweight and Obese Korean.pdf

Table 1 Characteristics of Women with BMI � 23 kg/m2 in 2008 KNHANES IV(N ¼ 1,739)

Demographics M or % (SE) Range

Age (yr), M 49.79 (0.55) 20.00 e 93.00�40 28.3 (1.56)41e65 54.1 (1.52)�66 17.7 (1.19)

Marital status (married & living together), % 71.1 (1.30) e

Education (high school or less), % 82.3 (1.31) e

Below poverty levela, % 25.4 (1.46) e

Work status (yes) 45.8 (1.44)Current smoker, % 6.6 (0.86)BMI (kg/m2), M 25.88 (0.08) 23.00 e 40.5423 � BMI < 25, % 44.5 (1.47)BMI � 25, % 55.5 (1.47)

Body weight perception e

Underweight 3.7 (0.49)About right 21.5 (1.12)Overweight 56.3 (1.23)Obese 18.6 (1.12)

Weight loss efforts (yes) 59.5 (1.48) e

Note. BMI ¼ body mass index; KNHANES ¼ Korea National Health and NutritionExamination Survey IV; SE ¼ standard error.

a Below poverty level ¼ a poverty-income ratio of less than 1.

S. Boo / Asian Nursing Research 7 (2013) 191e197 193

Covariates

Covariates of interest were age, marital status, education level,poverty level, work status, and smoking status. In particular, noofficial poverty line has been defined in Korea, so the concept ofpoverty income ratios (PIR) was used to define poverty level for thisstudy. The PIR represents the ratio of family income adjusted byfamily size to the poverty threshold, which is based on the mini-mum cost of living as established by the Ministry of Health andWelfare (KRW 1,400,000 per month for a household of four people,i.e., approximately US$ 1,230 per month). Ratios below 1 indicatethat the income for the respective family is below the povertythreshold and were defined as being below the governmentpoverty level in this study. A ratio of 1 or greater is above thepoverty level. Women were considered current smokers if theyreported that they were currently smoking.

Data analysis

Statistical analyses were performed using SPSS Complex Sam-ples 19.0 (SPSS Inc., Chicago, IL, USA). All study variables werescreened for missing data, outliners, and suspected errors. TheKNHANES IV used a stratified, multistage probability samplingdesign. Thus, data were weighted to generate appropriate popula-tion estimates. Weighted means or percentages were presented todescribe participant characteristics. Chi-square tests were used toassess the associations among objective weight status based onBMI, self-perceived weight status, and weight loss efforts.

Table 2 Bivariate Relationships among BMI, Body Weight Perception, and Weight Loss Effor

Variables BMI, % (SE) p

Overweighta Obesity Ov

Weight loss efforts (yes) 55.4 (2.06) 62.7 (1.83) .004 29Body weight perceptionUnderweight 5.3 (0.84) 2.4 (0.51) <.001About right 31.2 (1.97) 13.7 (1.15)Overweight 58.3 (2.14) 54.7 (1.49)Obese 5.3 (1.04) 29.2 (1.66)

Note. BMI ¼ body mass index; SE ¼ standard error.a Overweight ¼ 23 kg/m2 � BMI < 25 kg/m2; obesity ¼ BMI � 25 kg/m2.

Spearman’s r correlations were used to describe univariate re-lationships among BMI, body weight perception, weight loss ef-forts, and covariates.

To test the mediating role of body weight perception, a series ofthree regression analyses specified by Baron and Kenny (1986)were performed. The first model regressed weight perception(the mediator) on BMI (the independent variable). The secondequation regressed weight loss efforts (the dependent variable) onBMI. The third equation regressed weight loss efforts on both BMIand weight perception. To establish mediation, the following con-ditions should be met: The independent variable (BMI) is a signif-icant predictor of themediator (body weight perception) in the firstequation. The independent variable (BMI) is a significant predictorof the dependent variable (weight loss efforts) in the secondequation. The mediator (body weight perception) is a significantpredictor of the dependent variable (weight loss efforts), and thestrength of the relationship between the dependent variable(weight loss efforts) and the independent variable (BMI) is signif-icantly reduced with the addition of the mediator variable in thethird equation (Baron & Kenny). For the first equation, an orderedlogistic regression model was used to assess the predictive effectsof BMI on weight perception as an ordered, four-category responsevariable (underweight, about right, overweight, & obese). Thesecond and third equations were examined with logistic re-gressions, as weight loss efforts were a dichotomous variable. Sig-nificant covariates with the dependent variable (p > .05) from theSpearman’s r correlations were simultaneously entered into allregression models to control for their effects.

Results

Table 1 shows the characteristics of participants of Koreanwomenwith BMI � 23 kg/m2. The mean age was 49.79 years. Morethan half (54.1%) were between 41 and 65 years old. About 70% ofthe women were married and living with their spouses. The ma-jority (82.3%) of them had an education level of high school or less.Less than half (45.8%) were employed, and 25.4% of the womenwould be considered as having low incomes below the povertylevel as defined by PIR. The rate of current smokers was 6.6%.Approximately 45% were classified as overweight and 55% as obese,although significantly less (18.6%) perceived themselves as obese,and 56.3% perceived themselves as overweight and 25.2% as un-derweight or about right. Overall, two out of every five womenreported that they were trying to lose weight.

Bivariate relationships among BMI, weight perception, andweight loss efforts are presented in Table 2. Three variables weresignificantly associated with each other. Obese women are morelikely to report that they were trying to lose weight (62.7%)compared to overweight women (55.4%, p ¼ .004). Among over-weight women, 36.5% reported themselves as underweight orabout right, 58.3% as overweight, and 5.3% as obese. Among obese

ts (N ¼ 1,739)

Body weight perception, % (SE) p

erweight About right Underweight Obese

.8 (1.19) 40.8 (3.19) 65.6 (1.85) 68.3 (3.13) <.001

Page 4: Body Mass Index and Weight Loss in Overweight and Obese Korean.pdf

Table 4 Ordered Logistic Regression Analysis That Predicts Body Weight Perception inKorean Women with BMI � 23 kg/m2 in 2008 KNHANES IV (N ¼ 1,739)

Variables OR 95% CI p

BMIa

Overweight 1.00Obesity 5.47 (4.46, 6.69) <.001

Age 0.93 (0.92, 0.94) <.001Married & living together 1.02 (0.94, 1.11) .907High school or less 0.97 (0.72, 1.02) .860Below poverty level 0.92 (0.74, 1.13) .517

Note. BMI ¼ body mass index; KNHANES ¼ Korea National Health and NutritionExamination Survey; OR ¼ odds ratio; CI ¼ confidence interval.

a Overweight ¼ 23 kg/m2 � BMI < 25 kg/m2; obesity ¼ BMI � 25 kg/m2.

S. Boo / Asian Nursing Research 7 (2013) 191e197194

women, 29.2% perceived their body weight status correctly; 54.7%perceived themselves to be overweight and 16.1% as underweightor about right. The proportion of women trying to lose weightdiffered significantly by body weight perception (p< .001). Womenwho reported higher perceived weight were more likely to reportthat they were trying to lose weight.

Table 3 shows the results of Spearman’s correlations amongstudy variables. Dependent variable, weight loss efforts, wasnegatively related with age, marital status, education and povertylevel. Weight perceptionwas positively related with age, education,and poverty level. Significant covariates were entered into thefollowing regression models to control for their effects.

Table 4 displays the results of the ordered logistic regressionwith body weight perception as an ordered, four-category responsevariable (underweight, about right, overweight, & obese). Obesewomen were 5.47 times more likely to report one unit heavier onthe level of weight perception compared to overweight women(odds ratio [OR] ¼ 5.47, 95% CI: 4.46, 6.69), when all other variablesin the model were held constant. This result supports the firstcondition of mediation. The results of multiple logistic regressionanalyses performed to examine the second (model 1) and thirdconditions (model 2) of mediation are presented in Table 5. Obesewomenwere 1.82 times more likely to be trying to lose weight thanoverweight women were, after controlling for all other variables inmodel 1 (OR ¼ 1.82, 95% CI: 1.48, 2.24). However, the associationsbetween BMI and weight loss efforts became weaker when bodyweight perception was added into the model (model 2: OR ¼ 1.31,95% CI: 1.11, 1.71), and weight perception was independently andpositively associated with trying to lose weight. Women who re-ported themselves to be overweight in comparison to women whoreported themselves as underweight were 2.83 timesmore likely tobe trying to lose weight (OR ¼ 2.83, 95% CI: 1.65, 4.84), controllingfor all other variables in the model. Women who reported them-selves to be obese in comparison to women who reported them-selves to be underweight were 3.39 times more likely to be tryingto lose weight (OR ¼ 3.39, 95% CI: 1.87, 6.17) after controlling forcovariates.

Discussion

This study attempted to enhance our understanding of the re-lationships among actual body weight, weight perception, andweight loss efforts as well as to test the plausibility of themediatingrole of body weight perception on the relationship between actualbody weight and weight loss efforts in a national sample of Koreanwomenwho are overweight or obese. A mediator is a third variablethat comes between the independent and dependent variables.Researchers are interested in investigating mediators when theywant to explain “how” and “why” the relationships between theindependent and dependent variables occur, especially when a

Table 3 Spearman’s Correlations between Study Variables

Variables Weight lossefforts

BMI Body weightperception

A

Weight loss efforts 1.000 0.118** .288** �.2BMI 1.000 .439** �.3Body weight perception 1.000 .0Age 1.0Marital statusEducationBelow povertyWork statusCurrent smoker

Note. BMI ¼ body mass index.*p < .01.**p < .001.

significant relationship exists between the two variables (Baron &Kenny, 1986). The mediation models presented in this study werefound to be a plausible explanation of the relationships amongvariables of interest. Similar to previous reports (Andreyeva et al.,2010; Bersamin et al., 2010; Bish et al., 2005; Koo & Park, 2011),the level of overweight measured by BMI is a significant correlate ofweight loss efforts. In addition, the relationship between BMI andweight loss efforts was partially mediated through body weightperception. The findings of this study suggest that promotingweight loss interventions in Korean womenwho are overweight orobese should take into consideration their weight perception.

The overall prevalence of weight loss efforts in this nationalsample of Korean women was 59.5%. The rate was higher in obesewomen (62.7%) than that in overweight women (55.4%). The stronglinear relationship between the level of overweight and weight lossefforts found in this study was consistent with those of previousstudies conducted with other samples (Andreyeva et al., 2010; Bishet al., 2005). However, the prevalence of weight loss efforts in thisstudy was somewhat lower than those in studies by Bish et al. andAndreyeva et al., who both analyzed national samples of Americanwomen and reported that 60% of overweight and 70% or more ofobese American women were trying to lose weight. One reason forthe relatively lower rate of weight loss efforts in Korean womenmay be due in part to the different BMI cut-points for overweightand obesity used in this study. Asians such as Koreans have a higherpercentage of body fat and more centralized fat distributioncompared to Caucasians of the same sex, age, and BMI. Thus, theirrisk for obesity-associated diseases is high even at a lower BMI(WHO Expert Consultation, 2004). Korean women with a BMI of23 kg/m2 already have a three-fold increased risk for having threeor more cardiovascular risk factors compared to those with aBMI < 21 kg/m2 (Park, Yun, Park, Kim, & Choi, 2003). Thus, forKoreans, overweight is defined as 23 kg/m2 � BMI < 25 kg/m2 andobesity is BMI � 25 kg/m2 (WHO, 2000). Korean women should beinformed about the specific cut-points for overweight and obesityin Koreans. They should be aware that their risk for obesity-

ge Maritalstatus

Education Belowpoverty

Workstatus

Currentsmoker

89** �.090** �.142** �.161** .039 �.03278** �.086** �.158** �.109** .020 .04072* .040 .078* .099** .013 �.00100 .285** .425** .310** .162** �.087**

1.000 .076* .157** .110** .067*1.000 .201** .030 .015

1.000 .029 �.0141.000 �.028

1.000

Page 5: Body Mass Index and Weight Loss in Overweight and Obese Korean.pdf

Table 5 Multiple Logistic Regression Analysis That Predicts Weight Loss Efforts inKorean Women with BMI � 23 kg/m2 in 2008 KNHANES IV (N ¼ 1,739)

Variables Model 1 Model 2

OR 95% CI p OR 95% CI p

BMIa

Overweight 1.00 1.00Obesity 1.82 (1.48, 2.24) <.001 1.31 (1.11, 1.71) <.022

Body weight perceptionUnderweight 1.00About right 1.24 (0.71, 2.14) .406Overweight 2.83 (1.65, 4.84) <.001Obese 3.39 (1.87, 6.17) <.001

Age 0.92 (0.90, 0.97) <.001 0.94 (0.91, 0.98) <.001Married & living together 1.00 (0.91, 1.09) .726 1.00 (0.90, 1.08) .669High school or less 0.85 (0.61, 1.18) .325 0.88 (0.63, 1.23) .461Below poverty level 0.66 (0.52, 0.83) <.001 0.67 (0.53, 0.85) .001

Note. BMI ¼ body mass index; KNHANES ¼ Korea National Health and NutritionExamination Survey; OR ¼ odds ratio; CI ¼ confidence interval.

a Overweight ¼ 23 kg/m2 � BMI < 25 kg/m2; obesity ¼ BMI � 25 kg/m2.

S. Boo / Asian Nursing Research 7 (2013) 191e197 195

associated disease is high even though they may look thinner thanCaucasians. If there is a discrepancy between the actual level ofobesity and perceived body weight, the gap should be closed inorder to optimize health.

In this study, the relationship between BMI and body weightperception was assessed. Previously, few investigations haveexamined this relationship in adult Korean women. Although BMIwas significantly associated with weight perception before andafter controlling for covariates in this study sample, a large pro-portion of overweight or obese women perceived themselvesinaccurately. The majority of women thought they weighed lessthan they really did. The heavier they were, the more likely theywere to underestimate their weight (Table 2). Overall 58.3% ofoverweight and 29.2% of obese women correctly classified theirweight, while 36.5% of overweight and 70.8% of obese womenunderestimated their weight. These findings are consistent with astudy by Lemon et al. (2009), who reported that overweight orobese women in the United States underestimate their weightwhereas women with normal weight tend to overestimate it(Lemon et al.). Overweight or obese women who underestimatetheir weight might be the group that in particular needs nursinginterventions that target the accuracy of body weight perceptionand obesity-associated health risks as the underestimation ofweight in overweight women is significantly related to a lowerlikelihood of weight-control behaviors (Kim et al., 2008; Wanget al., 2009).

The underestimation of body weight in women can also be acritical problem because their misperception may not be limited tohow they view themselves. A recent meta-analysis showed thatoverweight or obese mothers were more likely to have overweightor obese children. More importantly, they were more likely to un-derestimate their child’s excess weight compared tomothers with ahealthy weight (Doolen, Alpert, & Miller, 2009). If mothers under-estimate their child’s weight, they are unlikely to advise their childto lose weight. This would likely contribute to the current epidemicof obesity in Korea could continue.

The underestimation of weight in women was related withadvancing age, lower income levels, and lower level of education(Chang & Christakis, 2003). Although this study did not aim toassess the effect of covariates on the dependent variables, only agewas found to be statistically significant and independently associ-ated with body weight perception in Korean women: Educationand poverty level were not significantly related to body weightperception (Table 4). Older women are more likely to rate them-selves at a lower weight-perception category compared to younger

women. It is assumed that, as overweight and obesity becomemorecommon with advancing age, older women carrying unhealthyextra weight might change their perceptions of normal weight.They might think that being chubby is healthy and ideal. Comparedto a previous study among Koreans (Kim et al., 2004), the currentstudy included more women who underestimated their weight.Kim et al. reported that 23.3% of overweight and 55.9% of obesewomen underestimated their weight status, compared to 68.3% ofoverweight and 44.1% of obese women who correctly identifiedtheir weight status. This result might be partially attributable to thedifference in age of the study samples. Approximately 18% of thesample in the current study were women aged 66 or older, whichcould have affected the results. The role of age in the relationshipsamong BMI, body weight perception, and weight loss behaviors inKorean women may be an area in need of additional study.

The final logistic regression model (Table 5, model 2) in thisstudy revealed that level of overweight and body weight percep-tion were significant correlates of weight loss efforts. In this publicsample of Korean women, weight perception was a better correlateof weight loss efforts than BMI. Perceiving themselves to be over-weight or obese, compared to perceiving themselves to be under-weight, was strongly related with weight loss efforts. Previousstudies have demonstrated that perceptions of overweight orobesity increased the likelihood of trying to lose weight (Lee et al.,2005; Wang et al., 2009). Another study reported that perceptionsof overweight or obesitydindependent of BMI in Korean middle-aged womendwere related to increased use of undesirableweight-control behaviors, such as skipping meals or taking laxa-tives (Kim et al., 2008). Weight loss nursing interventions shouldconsider strategies that have the potential to promote accurateweight perception as well as desirable weight control behaviors.Current guidelines recommend that all overweight or obese in-dividuals trying to lose weight use increased physical activity andreduced caloric intake (Korean Endocrine Society and KoreanSociety for the Study of Obesity, 2010; National Heart, Lung, andBlood Institute, 1998). This study made no attempts to evaluateactual weight control behaviors, relying on self-reporting of weightloss efforts. Further research is warranted to examine whether self-reporting of weight loss efforts is a reliable estimate of actualweight loss behaviors in Koreanwomen and whether efforts to loseweight involve desirable or undesirable behaviors.

Following the statistical framework proposed by Baron andKenny (1986), this study revealed that, among Korean womenclassified as overweight and obese, the association between BMIand weight loss efforts is mediated by weight perception. Giventhat women’s age affects weight perception and weight loss efforts(Tables 4 and 5) and this study includes women in awide age range,subgroup analyses with three age groups (age �40 years, 41e65years, & �66 years) were performed to see if such a mediatingrelationship was still effective regardless of age (the result was notincluded here). As a result, weight perception mediated the rela-tionship between BMI and weight loss efforts in all age groups,even though the extent of effect was slightly different by group.Therefore weight perception is a very important and modifiablefactor in controlling body weight for Koreanwomen. This finding issimilar to Lee et al.’s (2005) findings. Although they did not aim toexamine the mediating role of body weight perception, in theirregression model, BMI was not a significant correlate of weight lossefforts when BMI and body weight perception were entered in theregression model at the same time (Lee et al.). In the current study,the odds ratio of BMI on weight loss efforts decreased from 1.8 to1.3 when body weight perception was considered. The decreasedodds ratio confirms that body weight perception mediates the as-sociation between BMI and weight loss efforts in this study sample.In addition, BMI was still a significant correlate of weight loss

Page 6: Body Mass Index and Weight Loss in Overweight and Obese Korean.pdf

S. Boo / Asian Nursing Research 7 (2013) 191e197196

efforts after body weight perception was controlled for, indicatingpartial mediation (Baron & Kenny). The findings of this study sug-gest that Korean women who are overweight or obese but who failto perceive themselves as such are less likely to try to lose weight.Nurses designing weight loss interventions should consider notonly the actual level of overweight, but also weight perceptions.The rising obesity epidemic in Korean women can be controlled byinitiating appropriate weight loss efforts in the early stages ofoverweight and maintaining them thereafter. Body weightperception can be used as a motivator for self-initiated weight lossefforts in Korean women. In particular, for those who inaccuratelyperceive their weight, providing healthy weight ranges for eachheight could be a good way to foster accurate weight perceptionand assist in setting weight loss goals.

This study has several limitations that must be acknowledged.First, this study relied on self-reports of trying to lose weight as anestimate of actual weight loss behaviors. Further research is war-ranted to examine whether self-reported weight loss efforts are areliable estimate of actual weight loss behaviors in Korean womenand whether their behaviors involve desirable or undesirable ef-forts. Second, body weight perception is likely a multi-dimensionalconcept that captures several elements. It may also be influenced byothers or the dominant culture. The KNHANES provides a singleassessment of weight perception; a stronger assessment of weightperception could produce different results. Third, this is a cross-sectional study. As such, causality should not be implied. Forexample, this study demonstrated that perception of obesity isrelated to increased likelihood of trying to lose weight. Reasonably,perceived obesity couldmotivate individuals to loseweight, but it isalso possible that those trying to lose weight might think they areobese. However, the greatest strength of this study is the use of anationally representative sample of Korean women rather thanselected overweight or obese women. Data were also weighted toincorporate sampling designs into the analyses. Thus, this studyproduces an appropriate population level of estimates. In addition,this study systematically followed the statistical steps developed byBaron and Kenny (1986). As such, nursing researchers interested ininvestigating mediators can use this study as an example.

Conclusion

This study found complex relationships among BMI, bodyweight perception, and weight loss efforts in Korean women withoverweight or obesity. BMI and body weight perception were sig-nificant correlates of weight loss efforts. BMI was significantlyassociatedwith weight perception, but a large proportion of Koreanwomen underestimated their weight. Korean women who areoverweight or obese but fail to perceive themselves as such are lesslikely to try to lose weight. Those who underestimate their weightneed to be informed regarding the definition of healthy bodyweight. In testing for mediation, weight perception did perform asa partial mediator in the relationship between BMI and weight lossefforts in Korean women. In addition to BMI, appropriate bodyweight perceptions could therefore be crucial points of focus for thedesign and implementation of nursing weight loss interventions.The rising obesity epidemic in Korean women might be controlledthrough self-initiated appropriate weight loss efforts. Body weightperception can be used as a motivator in such efforts. In addition,other mediators such as age need to be identified and tested so thatthe relationship among BMI, body weight perception, and weightloss efforts can be further developed.

Conflict of interest

The author declares no conflict of interest.

Acknowledgment

This work was supported by the Gachon University ResearchFund of 2013 (GCU-2013-M021).

References

Anderson, L. A., Eyler, A. A., Galuska, D. A., Brown, D. R., & Brownson, R. C. (2002).Relationship of satisfactionwith body size and trying to lose weight in a nationalsurvey of overweight and obese women aged 40 and older, United States. Pre-ventive Medicine, 35(4), 390e396. http://dx.doi.org/10.1006/pmed.2002.1079

Andreyeva, T., Long, M. W., Henderson, K. E., & Grode, G. M. (2010). Trying to loseweight: diet strategies among Americans with overweight or obesity in 1996and 2003. Journal of the American Dietetic Association, 110(4), 535e542. http://dx.doi.org/10.1016/j.jada.2009.12.029

Baron, R. M., & Kenny, D. A. (1986). The moderatoremediator variable distinction insocial psychological research: conceptual, strategic, and statistical consider-ations. Journal of Personality and Social Psychology, 51(6), 1173e1182. http://dx.doi.org/10.1037/0022-3514.51.6.1173

Bersamin, A., Hanni, K. D., & Winkleby, M. A. (2010). Predictors of trying to loseweight among overweight and obese Mexican-Americans: a signal detectionanalysis. Public Health Nutrition, 12(1), 64e73. http://dx.doi.org/10.1017/S136898000800181X

Bish, C. L., Blanck, H. M., Serdula, M. K., Marcus, M., Kohl, H. W., & Khan, L. K. (2005).Diet and physical activity behaviors among Americans trying to lose weight:2000 behavioral risk factor surveillance system. Obesity, 13(3), 596e607. http://dx.doi.org/10.1038/oby.2005.64

Boo, S., & Froelicher, E. S. (2012a). Cardiovascular risk factors and 10-year risk forcoronary heart disease in Korean women. Asian Nursing Research, 6(1), 1e8.http://dx.doi.org/10.1016/j.anr.2012.02.001

Boo, S., & Froelicher, E. S. (2012b). Suboptimal attainment of cardiovascular diseaseprevention guideline goals in Korean women. Asian Nursing Research, 6(2), 49e54. http://dx.doi.org/10.1016/j.anr.2012.05.002

Chang, V. W., & Christakis, N. A. (2003). Self-perception of weight appropriatenessin the United States. American Journal of Preventive Medicine, 24(4), 332e339.http://dx.doi.org/10.1016/S0749-3797(03)00020-5

Clarke, L. H. (2002). Older women’s perceptions of ideal body weights: the tensionsbetween health and appearance motivations for weight loss. Ageing and Society,22(6), 751e773. http://dx.doi.org/10.1017/S0144686X02008905

Doolen, J., Alpert, P. T., & Miller, S. K. (2009). Parental disconnect between perceivedand actual weight status of children: a metasynthesis of the current research.Journal of the American Academy of Nurse Practitioners, 21(3), 160e166. http://dx.doi.org/10.1111/j.1745-7599.2008.00382.x

Hamman, R. F., Wing, R. R., Edelstein, S. L., Lachin, J. M., Bray, G. A., Delahanty, L.,et al. (2006). Effect of weight loss with lifestyle intervention on risk of diabetes.Diabetes Care, 29(9), 2102e2107. http://dx.doi.org/10.2337/dc06-0560

Kim, C. S., Jeong, T. H., Kim, M. C., & Park, J. W. (2004). Factors associated withdistorted self-perception of body weight in Korean adults. Journal of the KoreanAcademy of Family Medicine, 25(6), 462e468.

Kim, D. S., Kim, H. S., Cho, Y., & Cho, S. I. (2008). The effects of actual and perceivedbody weight on unhealthy weight control behaviors and depressed moodamong adult women in Seoul, Korea. Journal of Preventive Medicine and PublicHealth, 41(5), 323e330. http://dx.doi.org/10.3961/jpmph.2008.41.5.323

Kim, M. H. (2012). Eating habit, body image, and weight control behavior by BMI inKorean female high school students-using Korea youth risk behavior web-based survey 2010 data. Korean Journal of Food and Nutrition, 25(3), 579e589.

Koo, J. O., & Park, S. (2011). Analysis of BMI, body composition, weight control,dietary behaviors of adult women. Korean Journal of Community Nutrition, 16(4),454e465. http://dx.doi.org/10.5720/kjcn.2011.16.4.454

Korean Endocrine Society and Korean Society for the Study of Obesity. (2010).Management of obesity: 2010 recommendation. Endocrinology and Metabolism,25(4), 301e304.

Lee, R. E., Harris, K. J., Catley, D., Shostrom, V., Choi, S., Mayo, M. S., et al. (2005).Factors associated with BMI, weight perceptions and trying to lose weight inAfrican-American smokers. Journal of the National Medical Association, 97(1),53e61.

Lee, S. S., & Oh, K. J. (2004). The effect of shape and weight based self-evaluation andbody dissatisfaction on disordered eating behaviors of female university stu-dents. Korean Journal of Clinical Psychology, 23, 91e106.

Lemon, S. C., Rosal, M. C., Zapka, J., Borg, A., & Andersen, V. (2009). Contributions ofweight perceptions to weight loss attempts: differences by body mass indexand gender. Body Image, 6(2), 90e96. http://dx.doi.org/10.1016/j.bodyim.2008.11.004

Must, A., Spadano, J., Coakley, E. H., Field, A. E., Colditz, G., & Dietz, W. H. (1999). Thedisease burden associated with overweight and obesity. Journal of the AmericanMedical Association, 282(16), 1523e1529. http://dx.doi.org/10.1001/jama.282.16.1523

National Heart, Lung, and Blood Institute. (1998). Clinical guidelines on the identi-fication, evaluation, and treatment of overweight and obesity in adults: The evi-dence report. Retrieved October 09, 2012, from http://www.nhlbi.nih.gov/guidelines/obesity/index.htm

Page 7: Body Mass Index and Weight Loss in Overweight and Obese Korean.pdf

S. Boo / Asian Nursing Research 7 (2013) 191e197 197

Park, H. S., Yun, Y. S., Park, J. Y., Kim, Y. S., & Choi, J. M. (2003). Obesity, abdominalobesity, and clustering of cardiovascular risk factors in South Korea. Asia PacificJournal of Clinical Nutrition, 12(4), 411e418.

Pi-Sunyer, X., Blackburn, G., Brancati, F. L., Bray, G. A., Bright, R., Clark, J. M., et al.(2007). Reduction in weight and cardiovascular disease risk factors in in-dividuals with type 2 diabetes: one-year results of the look AHEAD trial. Dia-betes Care, 30(6), 1374e1383. http://dx.doi.org/10.2337/dc07-0048

Putterman, E., & Linden, W. (2004). Appearance versus health: does the reason fordieting affect dieting behavior? Journal of Behavioral Medicine, 27(2), 185e204.http://dx.doi.org/10.1023/B: JOBM.0000019851.37389.a7

Wang, Y., Liang, H., & Chen, X. (2009). Measured body mass index, body weightperception, dissatisfaction and control practices in urban, low-income African

American adolescents. BMC Public Health, 9, 183. http://dx.doi.org/10.1186/1471-2458-9-183

World Health Organization. (2000). The Asia-Pacific perspective: redefining obesityand its treatment. Retrieved October 09, 2012, from http://www.wpro.who.int/nutrition/documents/Redefining_obesity/en/index.html

World Health Organization Expert Consultation. (2004). Appropriate body-massindex for Asian populations and its implications for policy and interventionstrategies. The Lancet, 363(9403), 157e163. http://dx.doi.org/10.1016/S0140-6736(03)15268-3

Yoon, K. H., Lee, J. H., Kim, J. W., Cho, J. H., Choi, Y. H., Ko, S. H., et al. (2006). Epidemicobesity and type 2 diabetes in Asia. The Lancet, 368(9548), 1681e1688. http://dx.doi.org/10.1016/S0140-6736(06)69703-1