Effects of birth cohort and age on body composition in a sample of community-based elderly

Jingzhong Ding, Stephen B Kritchevsky, Anne B Newman, Dennis R Taaffe, Barbara J Nicklas, Marjolein Visser, Jung Sun Lee, Michael Nevitt, Frances A Tylavsky, Susan M Rubin, Marco Pahor, Tamara B Harris, Health ABC Study

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

BACKGROUND: The effect of the recent obesity epidemic on body composition remains unknown. Furthermore, age-related changes in body composition are still unclear.

OBJECTIVE: The objective was to simultaneously examine the effects of birth cohort and age on body composition.

DESIGN: A total of 1786 well-functioning, community-based whites and blacks (52% women and 35% blacks) aged 70-79 y from the Health, Aging, and Body Composition Study underwent dual-energy X-ray absorptiometry annually from 1997 to 2003.

RESULTS: At baseline, mean +/- SD percentage body fat, fat mass, and lean mass (bone-free) were 28 +/- 5%, 24 +/- 7 kg, and 56 +/- 7 kg, respectively, for men and 39 +/- 6%, 28 +/- 9 kg, and 40 +/- 6 kg for women. Mixed models were used to assess the effects of cohort and age-related changes on body composition. Later cohorts in men had a greater percentage body fat (0.32% per birth year, P < 0.0001) than did earlier cohorts. This cohort effect was due to a greater increase in fat mass than in lean mass (0.45 kg and 0.17 kg/birth year, respectively). With increasing age, percentage body fat in men initially increased and then leveled off. This age-related change was due to an accelerated decrease in lean mass and an initial increase and a later decrease in fat mass. Similar but less extreme effects of cohort and age were observed in women.

CONCLUSIONS: The combination of effects of both birth cohort and age leads to bigger body size and less lean mass in the elderly.

Original languageEnglish
Pages (from-to)405-410
Number of pages6
JournalThe American Journal of Clinical Nutrition
Volume85
Issue number2
Early online date1 Feb 2007
DOIs
Publication statusPublished - Feb 2007

Keywords

  • Aged
  • Aged, 80 and over
  • Aging
  • Body Composition
  • Body Size
  • Cohort Studies
  • Female
  • Humans
  • Male
  • Journal Article
  • Research Support, N.I.H., Extramural
  • Research Support, N.I.H., Intramural

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