Body Weight Perception and Quality of Life in Nurses of Nantong City, China: A Cross-Sectional Study

Background To explored associations of body weight perception with body mass index and quality of life among nurses. Methods A total of 456 nurses (18-55 years old (cid:0) were surveyed in a cross-sectional study in a hospital of Nantong City, China. Data on social-demographic characteristics, body mass index, body weight perception and quality of life were collected. Results Our study showed that 40.6% of nurses misconception their weight status. Married nurses were more likely than unmarried to underestimate their weight. Signicant disparity in mental health, vitality and mental component summary scores were found in nursers who underestimate their weight compared to those correctly perceived or over or who overestimate their weight. Conclusion Interventions should be designed to help nurse address body weight status misconception, thereby contributing to label themselves and patients as underweight, normal weight, overweight or obese correctly, and in turn, giving reasonable eating habits and physical activities health education.


Introduction
Obesity is a globalizing health challenge. It is also a known risk factor for the development of other diseases, including type 2 diabetes, CVD, gallstones, musculoskeletal disorders and certain cancers.1 According to BMI, the prevalence of general obesity and overweight among Chinese women was 14.3% and 17.7%, respectively.2 However, 64% of overweight and obese women underestimated their body weight status. 3 As reported, weight underestimation may be an important obstacle to effective weight management and prevention of weight-related chronic diseases.4 This kind of subjective evaluation of actual weight status is called body weight perception (BWP).5 A correct body weight perception means that people know their current weight status correctly, which is essential to promote healthy lifestyle behavior, optimal weight management and the prevention of weight-related diseases.6BWP was associated with body mass index (BMI).7 However, previous study showed the consistency between self-perceived and actual body weight status was poor.3 Therefore we were speci cally interested in the difference between BWP and actual body weight status in Chinese women.
In addition, previous studies also showed that participants who overestimate their body weight status had comparatively low health-related quality of life (QoL). 8,9 To our knowledge, the relationship between Qol and BWP in Chinese women have not been reported in previous studies.
Thus,this study attempted to explore the relationship between BMI and BWP in Chinese women. Furthermore, Qol of the participants was also explored in this study.

Methods
Study design, study setting and participants A cross-sectional hospital-based study was conducted among nursing staff in A liated Haian Hospital of Nantong University between January 2018 and February 2018. A self-report questionnaire was distributed to potential female participants. Cases were excluded on the basis of the following criteria Exclusion criteria: (1) age < 18 or >80 years at the time of interview; (2) pregnant and lactating women; (3) with the following complications (Diabetes, hypertension, dyslipidemia, cancer, pulmonary disease, cardiovascular disease, musculoskeletal disorders, etc.) that were evaluated by annual physical examination; and (4)those who did not complete the questionnaire. In total, 456 nurses were enrolled for investigation and completed questionnaires. The response rate is 72.4%. In compliance with the Helsinki declaration, all nurses were told about the concept of the study and signed an informed consent prior to commencement of the study. Approval to conduct this study was obtained from the Ethics Committee of the A liated Haian Hospital of Nantong University.

Sociodemographic characteristics
Age,marital status, income, level of education, height and weight were included in the present analyses.

Weight status
Nurses' self-reported height and weight as used to estimate self-report BMI(kg/m²). Previous studies have found that self-reported height and weight provided adequate estimates for actual height and weight in population-based epidemiological studies.10, 11 We classi ed the participants as underweight (BMI <18.5 kg/m2), normal weight (BMI 18.5-22.9 kg/m²), overweight (BMI 23.0-27.5 kg/m²) and obese (BMI ≥27.5 kg/m²) based on the WHO standards.12,13 Body weight perception Participants self-rated weight status were sorted as "underweight", "normal weight", "overweight" and "obese" according to a single questionnaire item:"How do you think of yourself in terms of weight?" Underestimation of body weight status was de ned as reporting at least one BMI category lower than the selfrated weight status. Overestimation of body weight status was de ned as reporting at least one BMI category higher than the self-rated weight status. Statistical analyses were conducted with SSPS 21.0. Descriptive statistics were calculated for all variables measured. Continuous variables were presented as means and standard deviations and were compared using t tests (normal distribution), or Mann-Whitney's test (skewed distribution). Categorical variables were presented as frequencies and percentages. Chi-square test was used to make comparison. One way ANOVA and post hoc tests (LSD test) were used to compare between BWP categorical and Qol. A P-value of <0.05 was considered statistically signi cant. The concordance between self-perceived body weight status and self-reported body weight status was assessed by the Kappa coe cient.

Sample characteristics
We investigated Chinese nurses in Nantong City. The mean age was 30.7 ± 7.23 years. We considered 4 age groups: 18-24 years(20.0%), 25-34 years (54.2%), 35-44 years(21.0%) and 45-55 years(4.8%). Education category was subdivided into Diploma of higher education (30.5%) and Bachelor degree(69.5%). The mean BMI was 21.98 ± 2.784 kg/m2 for the overall sample. For actual weight groups, BMI revealed 8.8% to be underweight, 20.2% to be overweight and 13.6% to be obese, which was calculated by self-reported weight and height. However, 11.0% perceived themselves as underweight, 36.4% perceived themselves as overweight and 3.7% perceived themselves as obese. Chi-square tests indicated signi cant differences in BMI category by age (χ² = 39.119, p < 0.001) and marital status (χ² = 17.406, p < 0.001). Chi-square tests revealed no signi cant difference in BWP by age (χ² = 10.112, p = 0.341), education (χ² = 2.132, p = 0.545), marital status(χ² =2.617, p = 0.455) and per-capital disposable income (χ² = 4.425, p = 0.619). The results are presented in Table 1. nurses were more likely than single nurses to overestimate their weight. Moreover, no signi cant difference was found between age, education and per-capital disposable income in consistency of BMI and BWP. The results are presented in Table 2.   One-way between subjects ANOVAs were conducted to compare the impact of overestimation, consistency and underestimation of body weight on physical and mental health as measured by the SF-36 sub-scales. There was a signi cant main effect for MH, VT and MCS at the p < 0.05 level (see Table 4). Post hoc comparisons using the LSD test indicated that the mean scores for the underestimation group were signi cantly higher than the overestimation group on MH, VT and MCS. Underestimation group were signi cantly higher than the consistency group for MH, VT, MCS and GH. (see Table 4).

Discussion
Main nding of this study In our study, there was a signi cant difference between BMI and BWP in Chinese nurses. 40.6% of our respondents didn't correctly identify their weight status. Married nurses were more likely than single nurses to overestimate their actual weight status. No associations were found between accuracy of BWP and age, education, per-capital disposable income. Nurses who underestimated their weight status reported higher quality of life scores in some sub-scale of SF-36 than nurse who correctly/ over-estimated their weight status.

What is already known on this topic
Existing US research reported that 49 % of overweight paediatricians didn't identify their weight status correctly. Another UK research reported that 32.5% of nurses identify their weight status incorrectly.Previous studies have found that accuracy of BWP was associated with age, education and per-capital disposable income. [15][16][17] Existing studies stated that obesity can lead to psychological, social, and medical problems that may negatively affect Qol. 18,19 What this study adds This was the rst study to to examine Chinese healthy nurses' misconceptions of weight status. The rate of nurses' interceptions of weight status was 40.6%, lower than other study from US,20 but higher than other study from UK. 21 The different rates of weight status misconception described by these studies may be explained by diversity in sample characteristics. However, nurse were health professionals, whose misconception of their own body weight could effect their identi cation of overweight patients.21 Thus correctly identi cation of body weight should be one of the basic skills of nurses to help patients with weight management.
We found that married nurses were more likely than single nurses to overestimate their actual weight status which may be in uenced by the weight labeling from their partners. Recent a study has pointed that the experience of weight labeling(i.e., merely being told one is"too fat" by others) might in uence the selfperception of body weight status.22 Moreover their partners' weight labeling may likely originate in the stereotypical image of slim girls. Married nurse had more chances to be told they are fat by partners in this traditional image. It is logical that married nurse easier to overestimate their body weight status than single nurses.
Previous studies have found that accuracy of BWP was associated with age, education and per-capital disposable income.15-17 These associations were not revealed in our 456patients. We expect that variations in study design and participants' demographic characteristics might be the reasons for the discrepancy.
The prevalence of body weight underestimation was 0.0%, 9.2%, 31.5%, and 80.6%, respectively, in the successive BMI groups. Compared with underweight and normal weight nurses, overweight and obese nurses were easier to underestimate their body weight .76.7% of the nurse in underestimation group were overweight and obese. 95.12% of the nurse in overestimation group were underweight and normal weight. Additionally, We also found that a mismatch exists between BMI and BWP, consistent with previous studies.21,23 Misconception of body weight is therefore likely to be an important consideration for understanding the effects of underweight, overweight and obesity in China. Some studies stated that obesity can lead to psychological, social, and medical problems that may negatively affect Qol.18,19 Interestingly, our study found that nurse who underestimated their weight status reported higher quality of life scores in some sub-scale of SF-36 than nurse who correctly/over-estimated their weight status. Since nurse who underestimated their weight status didn't recognize the association of being overweight to an unhealthy condition, with consequent better scores on the evaluation of MH, VT, MCS and GH domains. But nurse who overestimated their weight status considered they are overweight/obesity, which lead to a worse scores on some domains of SF-36.

Limitations of this study
A major limitation of this research was its cross-sectional design, which makes causality was not able to be determined. Second, a single question was used to assessed the BWP, which may be inadequate for describing body image. Third, only age, education, marital status and yearly income were considered in assessing the BWP association.

Conclusions
Our study showed that a discrepancy exists between BMI and BWP. Married women were more likely than single women to overestimate their weight. Women who overestimate their body weight with a lower mental health, vitality and mental component summary scores, GH. Thus, Interventions should be designed to help nurse improve weight management awareness and increase their awareness of actual weight categories, thereby contributing to label themselves and patients as underweight, normal weight, overweight or obese correctly, and in turn, giving reasonable eating habits and physical activities health education.

Declarations
Ethical Approval and Consent to participate The participants provided written, informed consent. Academic and Ethics Committee of A liated Haian Hospital of Nantong University, China, reviewed and approved this study.

Consent for publication
Not applicable.

Availability of supporting data
Data is available upon request to corresponding authors.

Competing interests
The authors have no con ict of interest regarding this study.

Funding
This work was supported by grants from the Nantong Health and Family Planning Commission(WKZD2018008) and A liated Haian Hospital of Nantong