Weight Loss Programs May Have Beneficial or Adverse Effects on Fat Mass and Insulin Sensitivity in Overweight and Obese Black Women

Benjamin Leon; Bernard V Miller 3rd; Gloria Zalos; Amber B Courville; Anne E Sumner; Tiffany M Powell-Wiley; Mary F Walter; Myron A Waclawiw; Richard O Cannon 3rd

doi:10.1007/s40615-014-0006-6

Weight Loss Programs May Have Beneficial or Adverse Effects on Fat Mass and Insulin Sensitivity in Overweight and Obese Black Women

J Racial Ethn Health Disparities. 2014;1(3):140-147. doi: 10.1007/s40615-014-0006-6. Epub 2014 Mar 5.

Authors

Benjamin Leon¹, Bernard V Miller 3rd², Gloria Zalos¹, Amber B Courville³, Anne E Sumner², Tiffany M Powell-Wiley¹, Mary F Walter⁴, Myron A Waclawiw⁵, Richard O Cannon 3rd¹

Affiliations

¹ Cardiovascular and Pulmonary Branch, National Heart, Lung, and Blood Institute, Building 10-CRC Room 5-3330, 10 Center Drive, Bethesda, MD 20892 USA.
² Diabetes, Endocrinology and Obesity Branch, Clinical Center; National Institutes of Health, Bethesda, MD USA.
³ Nutrition Department, Clinical Center; National Institutes of Health, Bethesda, MD USA.
⁴ Core for Clinical Laboratory Services, Clinical Center; National Institutes of Health, Bethesda, MD USA.
⁵ Office of Biostatistics Research, National Heart, Lung, and Blood Institute, Bethesda, MD USA.

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.

Design and 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 (S_I) was calculated from an insulin-modified intravenous glucose tolerance test using the minimal model.

Results: Baseline S_I (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. S_I for 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 (S_I +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 (S_I -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.

Keywords: Obesity; insulin sensitivity; intervention; race; women.