Original Full Length Article
The association between fat and lean mass and bone mineral density: The Healthy
, Yun-Mi Song
, Joohon Sung
, Kayoung Lee
, Youn Sic Kim
, Sung-Il Cho
Health Care Center, Konkuk University Medical Center, Konkuk University School of Medicine, Seoul, Republic of Korea
Department of Family Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
Department of Epidemiology, Graduate School of Public Health and Institute of Health and Environment, Seoul National University, Seoul, Republic of Korea
Department of Family Medicine, Busan Paik Hospital, Inje University College of Medicine, Busan, Republic of Korea
Received 1 September 2011
Revised 19 January 2012
Accepted 20 January 2012
Available online 28 January 2012
Edited by: Rene Rizzoli
The potential beneﬁcial effects of increased body weight on bone mineral density (BMD) conﬂict with the ad-
verse effects of obesity on various health outcomes, necessitating more speciﬁc evaluations of the association
between each body component and BMD. In the present study, we evaluated associations of lean mass (LM)
and fat mass (FM) with BMD in a Korean sample consisting of a total of 1782 men and women whose mean
(standard deviation) age was 43.2 (12.6) years. They were selected from the Healthy Twin Study, a nation-
wide Korean twin and family study. BMD, FM and LM were measured using dual-energy X-ray absorptiom-
etry. Quantitative genetic analysis and linear mixed analysis were performed with respect to familial
relationships and a wide range of probable covariates. Linear mixed analysis revealed that BMD was positive-
ly associated with both FM and LM at each region of BMD measurement (whole body, spine, arms, and legs)
in men, premenopausal women, and postmenopausal women. However, the association with BMD was
stronger for LM than FM. Both LM and FM had positive genetic correlations with BMD at each region, al-
though the correlation with BMD tended to be stronger for LM than FM. Together, these ﬁndings suggest
that increased LM, rather than FM, is more beneﬁcial for BMD in the Korean population and warrants further
study of the common genetic determinants of BMD and body composition.
© 2012 Elsevier Inc. All rights reserved.
Bone mineral density (BMD) is a major determinant of the risk of
bone fracture, which causes serious morbidity and mortality in the
elderly . Body weight has been proposed to be one of the important
predictors of BMD . Likewise, greater body weight increases
mechanical stress on the skeleton, which stimulates osteogenesis
through bone remodeling and leads to an increase in BMD .
However, despite the beneﬁcial effects of increased weight on BMD,
overweight status increases the risk of type 2 diabetes, cardiovascular
diseases, liver disease, and certain cancers of the colon, breast, corpus
uteri, and gallbladder [4,5]. In this regard, it is necessary to further dis-
entangle the relationship between body weight and BMD by evaluating
the respective effects of each main component of body weight – lean
mass (LM) and fat mass (FM) – on BMD, as the hazardous health effects
of obesity are driven mainly by fat tissue .
Studies of the relationship between body composition and BMD
consistently demonstrate a positive relationship between LM and
BMD [6–14], whereas FM exhibits a range of positive [11–13,15],
null [7,8], or inverse [10,14,16,17] associations with BMD. In addition,
some studies report the relative importance of LM compared to FM on
BMD [6,9,11,12], while other studies report contradictory results .
In order to give better insights into their relative contributions, an
examination of the shared genetic contributions between components
of body composition and BMD should be useful [18,19], especially
given the fact that LM [20–22],FM[20,22], and BMD [11,21,22] are
strongly inﬂuenced by genetic makeup. Presently, genetic correlations
between body composition and BMD have been evaluated in studies
of twins [11,22] or families [10,16], and several common genomic re-
gions associated with FM and BMD  or LM and BMD  have
been identiﬁed. However, the aforementioned studies were conducted
in Western populations whose genetic background as well as lifestyle
and prevalence of osteoporotic fracture might be materially different
from those of Asian populations .
In the current study, we evaluated the associations of FM and LM
with BMD using the dataset from the Healthy Twin Study. We
Bone 50 (2012) 1006–1011
⁎ Corresponding author at: Department of Family Medicine, Samsung Medical Center
and Center for Clinical Research, Samsung Biomedical Research Institute, Sungkyunkwan
University School of Medicine, 50 Ilwondong, Kangnamgu, Seoul 135-710, Republic of
Korea. Fax: +82 2 3410 0388.
E-mail address: firstname.lastname@example.org (Y.-M. Song).
8756-3282/$ – see front matter © 2012 Elsevier Inc. All rights reserved.
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