title: Weight Loss Programs May Have Beneficial or Adverse Effects on Fat Mass and Insulin Sensitivity in Overweight and Obese Black Women.
abstract: OBJECTIVE
  Weight loss interventions have produced little change in insulin sensitivity in black women, but mean data may obscure metabolic benefit to some and adverse effects for others. Accordingly, we analyzed insulin sensitivity relative to fat mass change following a weight loss program.
  
  
  METHODS
  Fifty-four black women (BMI range 25.9 to 54.7 kg/m2) completed the 6-month program that included nutrition information and worksite exercise facilities. Fat mass was measured by dual-energy X-ray absorptiometry, and insulin sensitivity index (SI) was calculated from an insulin-modified intravenous glucose tolerance test using the minimal model.
  
  
  RESULTS
  Baseline SI(range 0.74 to 7.58 l/mU-1•min-1) was inversely associated with fat mass (r= -0.516,p< 0.001), independent of age. On average, subjects lost fat mass (baseline 40.8 ± 12.4 to 39.4 ± 12.6 kg [mean ± SD],P< 0.01), but 17 women (32 %) actually gained fat mass. SIfor the group was unchanged (baseline 3.3 ± 1.7 to 3.2 ± 1.6,P= 0.67). However, the tertile with greatest fat mass loss (-3.6 kg, range -10.7 to -1.7 kg) improved insulin sensitivity (SI+0.3 ± 1.2), whereas the tertile with net fat mass gain (+0.9 kg, range -0.1 to +3.8 kg) had reduced insulin sensitivity (SI-0.7 ± 1.3) from baseline values (P< 0.05 by ANOVA).
  
  
  CONCLUSIONS
  Black women in a weight loss program who lose fat mass may have improved insulin sensitivity, but fat mass gain with diminished sensitivity is common. Additional support for participants who fail to achieve fat mass loss early in an intervention may be required for success.
authors.affiliation: Cardiovascular and Pulmonary Branch, National Heart, Lung, and Blood Institute, Building 10-CRC Room 5-3330, 10 Center Drive, Bethesda, MD 20892 USA.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Leon
authors.affiliation: Diabetes, Endocrinology and Obesity Branch, Clinical Center; National Institutes of Health, Bethesda, MD USA.
authors.forename: Bernard V
authors.initials: BV
authors.lastname: Miller
authors.affiliation: Cardiovascular and Pulmonary Branch, National Heart, Lung, and Blood Institute, Building 10-CRC Room 5-3330, 10 Center Drive, Bethesda, MD 20892 USA.
authors.forename: Gloria
authors.initials: G
authors.lastname: Zalos
authors.affiliation: Nutrition Department, Clinical Center; National Institutes of Health, Bethesda, MD USA.
authors.forename: Amber B
authors.initials: AB
authors.lastname: Courville
authors.affiliation: Diabetes, Endocrinology and Obesity Branch, Clinical Center; National Institutes of Health, Bethesda, MD USA.
authors.forename: Anne E
authors.initials: AE
authors.lastname: Sumner
authors.affiliation: Cardiovascular and Pulmonary Branch, National Heart, Lung, and Blood Institute, Building 10-CRC Room 5-3330, 10 Center Drive, Bethesda, MD 20892 USA.
authors.forename: Tiffany M
authors.initials: TM
authors.lastname: Powell-Wiley
authors.affiliation: Core for Clinical Laboratory Services, Clinical Center; National Institutes of Health, Bethesda, MD USA.
authors.forename: Mary F
authors.initials: MF
authors.lastname: Walter
authors.affiliation: Office of Biostatistics Research, National Heart, Lung, and Blood Institute, Bethesda, MD USA.
authors.forename: Myron A
authors.initials: MA
authors.lastname: Waclawiw
authors.affiliation: Cardiovascular and Pulmonary Branch, National Heart, Lung, and Blood Institute, Building 10-CRC Room 5-3330, 10 Center Drive, Bethesda, MD 20892 USA.
authors.forename: Richard O
authors.initials: RO
authors.lastname: Cannon
keywords: Obesity; insulin sensitivity; intervention; race; women
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