^*Department of Family and Preventive Medicine, and Cancer Prevention and Control Program, University of California, San Diego, La Jolla, California.

Correspondence: Cheryl L. Rock University of California, San Diego, 9500 Gilman Drive, Dept. 0901, La Jolla, CA 92093-0901. E-mail: clrock@ucsd.edu

^*The costs of publication of this article were defrayed, in part, by the payment of page charges. This article must, therefore, be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

By contractual agreement, scientists at the University of California, San Diego, have responsibility and independence regarding data management, analysis, and publication.

Received 19 June 2006; Revised  00; Accepted 31 October 2006.

Abstract

Objective: To test whether a commercial weight loss program promotes greater weight loss in overweight or obese women compared with control conditions and to describe the effect on plasma lipids, carotenoids, hormones, and fitness.

Research Methods and Procedures: Overweight or obese women were randomized to commercial weight loss program or control conditions (n = 35 each).

Results: At randomization, participants were 41.1 (11.4) (mean [ standard deviation] ) years, BMI 34.0 (3.5) kg/m², and weight 92.0 (11.1) kg. At 6 months, change in weight by intent-to-treat (ITT) analysis was - 7.2 (6.7) kg and - 7.8% (7.2% ) in the intervention group vs. - 0.3 (3.9) kg and - 0.3% (4.5% ) in the control group (n = 35 for each; p < 0.01). One-year ITT analysis revealed significantly greater change in weight, percent weight, BMI, and waist and hip circumferences in the intervention vs. control group. Completers at 1 year exhibited change in weight of - 7.3 (10.4) kg for the intervention group (n = 32) vs. - 0.7 (5.6) kg for controls (n = 33) (p < 0.01), and - 7.8% (11.1% ) weight change for the intervention group vs. - 0.7% (6.2% ) for controls (p < 0.01). High-density lipoprotein (HDL) cholesterol concentration increased significantly in the intervention group. Fasting serum insulin decreased in the intervention but increased in the control group at 6 months (p < 0.01), remaining different at 1 year (p = 0.05).

Discussion: The commercial program successfully facilitated weight loss, which was notably maintained at 1 year, and promoted favorable changes in plasma lipid and hormone concentrations.