Ethnic and age-related fat free mass loss in older Americans: the Third National Health and Nutrition Examination Survey (NHANES III)

BMC Public Health. 2005 Apr 19;5:41. doi: 10.1186/1471-2458-5-41.


Background: Although age-related loss of fat free mass (FFM) is well known, there is paucity of data on national estimates, and on the differential influence of ethnicity on the decline in FFM with increasing age. We determined whether age-related loss in FFM and fat free mass index (FFMI) vary by gender and or ethnicity, using representative data from the Third National Health and Nutrition Examination Survey (NHANES III).

Methods: Analyses were limited to 5,803 non-institutionalized, non-Hispanic Whites and African Americans (Blacks) over the age of 40 years. Body density was calculated from the sum of 3-skinfolds, and percent body fat estimated from body density. FFM was estimated by subtracting body fat from body weight, while FFMI was defined as FFM (kilograms) divided by the square of body height (meter2).

Results: Overall FFM and FFMI were significantly higher in black women than white women (P = 0.001; P = 0.001 respectively), but similar in black men compared to white men. Age-related decline in FFM reached significance level earlier in black men (at age 65-69) than white men (at age 70-74), and in black women (at age 70-74) than white women (at age 75-79). Similar decline in FFMI was noted in men and in women. In multivariate analyses, FFM significantly associated with ethnicity (p = 0.012) and with age (p < 0.001) in women, but only with age (p < 0.001) in men. In men and in women, FFMI significantly associated with ethnicity (p < 0.001; p = 0.003 respectively) and with age (p < 0.001; p = 0.004 respectively).

Conclusion: Age-related loss and decline in FFM and FFMI in older Americans is higher for black men and women, than for white men and women. The development of focused population-based preventive strategies is likely to improve functional independence in the aged.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • African Americans / genetics
  • African Americans / statistics & numerical data*
  • Age Factors
  • Aged
  • Aged, 80 and over
  • Anthropometry / methods*
  • Body Composition / genetics
  • Body Composition / physiology*
  • Body Mass Index*
  • Body Weight / genetics
  • Body Weight / physiology
  • Cross-Sectional Studies
  • European Continental Ancestry Group / genetics
  • European Continental Ancestry Group / statistics & numerical data*
  • Female
  • Humans
  • Male
  • Middle Aged
  • Muscles / physiopathology
  • Nutrition Surveys
  • Sex Factors
  • United States