1. ¹Department of Rehabilitative and Preventive Sports Medicine, University Hospital, Freiburg, Germany
2. ²Institute of Immunology, Universität Witten/Herdecke, Witten, Germany

Correspondence: Dr P Deibert, Department of Rehabilitative and Preventive Sports Medicine, University Hospital, Hugstetter Str. 55, D-79106 Freiburg, Germany. E-mail: deibert@msm1.ukl.uni-freiburg.de

Received 4 February 2004; Revised 22 June 2004; Accepted 23 June 2004; Published online 10 August 2004.

Abstract

OBJECTIVE: To determine change of weight, body composition, metabolic and hormonal parameters induced by different intervention protocols.

DESIGN: Randomized, controlled study including participants exhibiting a BMI between 27.5 and 35. Three different interventions containing lifestyle education (LE-G), or a substitutional diet containing a high-soy-protein low-fat diet with (SD/PA-G) or without (SD-G) a guided physical activity program.

SUBJECTS: A total of 90 subjects (mean weight 89.9 kg; mean BMI 31.5), randomly assigned to one of three treatment groups.

MEASUREMENTS: Change in body weight, fat mass and lean body mass measured with the Bod Pod^® device at baseline, 6 weeks and 6 months; change in metabolic and hormonal parameters.

RESULTS: In all, 83 subjects completed the 6-months study. BMI dropped highly significantly in all groups (LE-G: -2.21.43 kg/m²; SD-G: -3.11.29 kg/m²; SD/PA-G: -3.01.29 kg/m²). Subjects in the SD-G and in the SD/PA-G lost more weight during the 6-months study (-8.93.9; -8.93.9 kg) than did those in the LE-G (-6.24.2 kg), and had a greater decrease in fat mass (-8.84.27; -9.44.54 kg) than those in the LE-G (-6.64.59 kg). In contrast, no significant intraindividual or between-group changes in the fat-free mass were seen. In all groups, metabolic parameters showed an improvement in glycemic control and lipid profile.

CONCLUSIONS: Our data suggest that a high-soy-protein and low-fat diet can improve the body composition in overweight and obese people, losing fat but preserving muscle mass.