Fat mass increase in 7-year-old children: More bone area but lower bone mineral density

Hannes Hrafnkelsson, Gunnar Sigurðsson, Kristjan Th Magnusson, Emil L. Sigurdsson, Erlingur Johannsson*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)


The main aims of this study were, to evaluate what effect a change in fat mass (FM) and lean body mass (LBM) has on bone parameters over 2 years' time, in 7-year-old school children and to see what effect fitness had on bone parameters in these children. A repeated-measures design study was conducted where children born in 1999 from six elementary schools in Reykjavik, Iceland were measured twice. All children attending second grade in these six schools were invited to participate. Three hundred twenty-one children were invited, 211 underwent dual-energy X-ray absorptiometry (DXA) scans at the age of seven, and 164 (78 %) of the 211 had DXA scans again 2 years later. Increase in both FM and LBM was associated with increased total body bone mineral content (BMC) and bone area (BA). An increase in FM was more strongly positively associated with BA while an increase in LBM was more strongly associated with an increase in BMC. An increase in FM was negatively associated with change in bone mineral density (BMD), but an increase in LBM was positively associated with change in BMD. Fitness was positively associated with bone parameters when weight, height and sex were accounted for. The present results suggest that an increase in fat mass over 2 years is associated with an increase in BA and BMC, but a decrease in BMD in the whole body. An increase in LBM accrual, on the other hand, is positively associated with all bone parameters in the body. Fitness is associated with both BMC and BMD but not BA.

Original languageEnglish
Pages (from-to)442-448
Number of pages7
JournalJournal of Bone and Mineral Metabolism
Issue number4
Publication statusPublished - Jul 2013

Bibliographical note

Funding Information:
The study was primarily funded by the Icelandic Centre for Research (RANNIS), but also supported by the city of Reykjavik, the Ministry of Education, Science and Culture, The Icelandic Primary Health Care Research Fund and BRIM Seafood.

Other keywords

  • Bone area
  • Bone mineral content
  • Bone mineral density
  • Fat mass
  • Fitness


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