Differences in resting metabolic rates of inactive obese African-American and Caucasian women

J. N. Forman, W. C. Miller, L. M. Szymanski, B. Fernhall

Research output: Contribution to journalArticlepeer-review

Abstract

OBJECTIVE: To compare resting metabolic rates (RMR) of African-American (n = 25) and Caucasian (n = 22) premenopausal (35 ± 1 y, Mean ± s.e.m.) women who are obese (95.2 ± 2.9 kg, body mass index (BMI) = 34.7 ± 0.9, % body fat = 45.2 ± 0.9), inactive and free from metabolic disorders or medications that would affect heart rate or RMR. MEASUREMENTS: RMR and respiratory exchange ratio (RER) by indirect calorimetry, body composition by plethysmography, maximal aerobic capacity (VO(2max)) and girth measurements. RESULTS: Group mean comparisons were made with a Student's t-test or an ANCOVA, which controlled for individual differences in body weight and lean body mass (LBM). Significance was set at P < 0.05. Groups were not significantly different in age, height, weight, BMI, % body fat, fat mass, RER, VO(2max), resting heart rate, maximal heart rate; or chest, waist, hip, arm, thigh or calf circumferences. After adjusting for body weight, RMR (IO2/min) for African-Americans (0.254 ± 0.007) was significantly lower (9%) than for Caucasians (0.277 ± 0.008). After RMR (IO2/min) was adjusted for LBM, an even larger difference (-12%) persisted for African-Americans (0.250 ± 0.008) compared to Caucasians (0.281 ± 0.008). Predicted RMR (kJ/d) for the African-Americans was the same as measured RMR, whereas Caucasian women expended about 13% more energy than predicted. When controlling for LBM, the partial correlation between VO(2max) and RMR was r = 0.51 when VO(2max) was expressed as I/min, and r = 0.56 when VO(2max) was expressed as ml O2/kg/min, both highly significant (P < 0.000). CONCLUSION: The lower prevalence of obesity in Caucasian women may be due in part to a higher RMR as well as an under estimation of RMR in weight control therapy. Fitness level (VO(2max)) as well as LBM are significant predictors of RMR for both races.

Original languageEnglish (US)
Pages (from-to)215-221
Number of pages7
JournalInternational Journal of Obesity
Volume22
Issue number3
DOIs
StatePublished - 1998

Keywords

  • African-American women
  • Caucasian women
  • Metabolic rate
  • Metabolism
  • Obesity
  • Racial differences

ASJC Scopus subject areas

  • Medicine (miscellaneous)
  • Endocrinology, Diabetes and Metabolism
  • Nutrition and Dietetics

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