Relationship between indices of obesity obtained by anthropometry and dual-energy X-ray absorptiometry: The Fourth and Fifth Korea National Health and Nutrition Examination Survey (KNHANES IV and V, 2008–2011)

doi:10.1016/j.orcp.2014.11.002

Obesity Research & Clinical Practice

Volume 9, Issue 5, September–October 2015, Pages 487-498

https://doi.org/10.1016/j.orcp.2014.11.002 Get rights and content

Summary

Background

Body mass index (BMI), waist circumference (WC), and even dual-energy X-ray absorptiometry (DXA) are used for obesity diagnosis. However, it is not known which DXA-derived index of obesity correlates best with BMI and/or WC and it is not clear whether such an index is accurate or not.

Objectives

The aim of this study is to show the relationship between anthropometric measurements (BMI, WC) and body fat indices from DXA and to determine which DXA indices are strongly related to BMI and WC.

Subjects

This study was based on data obtained from the Fourth and Fifth Korea National Health and Nutrition Examination Survey (KNHANES IV-V). DXA measurements were performed on survey subjects over 10 years old from July 2008 through to May 2011. Of these, 18 198 individuals, aged 19 years and older for whom DXA data were available, were included.

Methods

Weighted Pearson's correlated coefficients (r) were calculated among indices, according to sex, age group and menopause, and the coefficients were compared with each other.

Results

BMI correlates most with trunk body fat mass in kg (r = 0.831) and then with total body fat in kg (r = 0.774, P < 0.00043 for difference of r). In the older age group, BMI correlates with total body fat mass (r = 0.822) better than with trunk fat mass (r = 0.817, P < 0.00043). WC correlates with trunk body fat mass most in both genders and all age groups (0.804 ≤ r ≤ 0.906). Correlations of BMI (r = 0.645 for men, 0.689 for women) and WC (r = 0.678 for men, 0.634 for women) to body fat percentages (%) were less robust than those to body fat mass.

Conclusions

BMI and WC reflect trunk and total body fat in kg more than body fat percentage derived by DXA.

Introduction

Obesity is defined as the status of excessive fat accumulation in body, however, body mass index (BMI) and waist circumference (WC) as surrogate measures of obesity and central obesity, respectively, do not quantify the amount or the percentage of body fat. However, the measurement of BMI and WC are very easy and cost-effective, and these two indices have been shown to be closely related to the risk of mortality and morbidity in numerous epidemiological studies [1], [2], [3].

While both BMI and WC have significant clinical applications, these have inherent limitations as indirect methods in the diagnosis of obesity. Dual-energy X-ray absorptiometry (DXA), computed tomography (CT), and magnetic resonance imaging (MRI) are the direct methods of body fat assessment. Even though CT and MRI can measure adipose tissue amount very accurately, especially the compartmental adipose tissue amount such as the visceral adipose tissue or the ectopic fat accumulation in a specific organ, they are cost-prohibitive at a population level, time-consuming, and often inappropriate for the measurement of total body fat. On the contrary, DXA is an accurate method of body fat assessment [4], is able to measure not only the total body fat but also the regional body fat [5], and is less costly and time-consuming compared to CT or MRI. In addition, bone density can also be measured with DXA equipment and it is widely available in many clinical facilities.

In spite of wide usage of BMI, WC, and DXA in obesity diagnosis, few studies have investigated which DXA-derived index is reflected well by BMI or WC and the strength of the relationships between them. Previous studies reported that both of BMI and WC were significantly correlated with percentage of total body fat in a large representative US population, and BMI was highly correlated with total body fat mass in narrow populations [6], [7], [8]. However, as far as we know, there is no study focused on the relationship between anthropometric measurements and DXA indices of total and regional body fat in a large population. The aim of this study is to show the relationship between anthropometric measurements and body fat indices from DXA, and to determine which DXA indices are strongly related to BMI and WC.

Section snippets

Study subjects

The Korea National Health and Nutrition Examination Survey (KNHANES) is a nationwide survey representing the non-institutionalized population of Korea, with a stratified multistage probability-sampling design, conducted by the Ministry of Health and Welfare of Korea and the Korea Centers for Disease Control and Prevention, conducted periodically since 1998. KNHANES IV were performed in 2007–2009 and KNHANES V in 2010–2012, and the detailed sampling procedures of KNHANES IV and V have been

Characteristics of subjects

A total of 18 198 subjects, 19 years or older, were analyzed as a whole group. Subgroup analyses were performed according to gender, menopausal status and age groups. Subject characteristics are shown in Table 1.

Correlation between BMI and DXA indices, between WC and DXA indices

Plots of total and trunk BF mass against BMI show positive and very strong linear relations in the combined group and both genders (Fig. 1B and C). On the other hand, BMI has a weaker positive association with total BF percentage and TF/LF (Fig. 1A and D). Between BMI and total BF

Discussion

In general, BMI has been accepted as reflecting total body fat [13], [14] whilst WC reflected visceral fat [15], [16], [17]. In this study, we show that BMI and WC reflect DXA-derived fat indices of not only total body fat mass but also trunk body fat mass in kg very well. Independently, BMI explains around 70% of the variation in total body fat mass and trunk fat mass in the Korean population. Simultaneously, WC can also explain over 60% variation of total and trunk fat mass regardless of sex,

Conflict of interest

The authors declare no conflict of interest.

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Original ArticleRelationship between indices of obesity obtained by anthropometry and dual-energy X-ray absorptiometry: The Fourth and Fifth Korea National Health and Nutrition Examination Survey (KNHANES IV and V, 2008–2011)

Summary

Background

Objectives

Subjects

Methods

Results

Conclusions

Introduction

Section snippets

Study subjects

Characteristics of subjects

Correlation between BMI and DXA indices, between WC and DXA indices

Discussion

Conflict of interest

Am J Clin Nutr

Am J Clin Nutr

Am J Cardiol

Am J Clin Nutr

Am J Clin Nutr

Am J Clin Nutr

Association of all-cause mortality with overweight and obesity using standard body mass index categories: a systematic review and meta-analysis

JAMA

The incidence of co-morbidities related to obesity and overweight: a systematic review and meta-analysis

BMC Public Health

Waist circumference and all-cause mortality in a large US cohort

Arch Intern Med

Comparison of body composition methods: a literature analysis

Eur J Clin Nutr

Measurement of soft tissue composition by dual energy X-ray absorptiometry

Br J Nutr

Comparison of body fatness measurements by BMI and skinfolds vs dual energy X-ray absorptiometry and their relation to cardiovascular risk factors in adolescents

Int J Obes

Relation of BMI to a dual-energy X-ray absorptiometry measure of fatness

Br J Nutr

Relationship between serum 25-hydroxyvitamin D and lung function among Korean adults in Korea National Health and Nutrition Examination Survey (KNHANES), 2008–2010

J Clin Endocrinol Metab

Original Article
Relationship between indices of obesity obtained by anthropometry and dual-energy X-ray absorptiometry: The Fourth and Fifth Korea National Health and Nutrition Examination Survey (KNHANES IV and V, 2008–2011)