The objective of this study was to dissociate the effects of weight loss (negative energy balance) and reduction in body fat mass on inflammatory markers. For that purpose, 33 (men: n=16; women: n=17) obese subjects underwent a weight loss program for 20 weeks. Weight reduction was divided into 4 phases: an 8-week low-energy diet, a 4-week weight maintenance diet, an additional 4-week low-energy diet and finally a 4-week weight maintenance diet. Body weight was reduced by 13.7 kg (p<0.0001) after the 8-week low-energy diet and by an additional 2.9 kg during the second weight reduction phase. The reduction in C-reactive protein (CRP) concentrations was significant after the second low-energy diet period (-35%, p=0.02) and was maintained after the following 4-week weight maintenance period. Interleukin-6 was only significantly reduced at the end of the study (-21%, p=0.02). Decreases in CRP and interleukin-6 were not associated with reduction in body weight but rather were associated with reduction in fat mass. Finally, adiponectin was not significantly altered during the intervention protocol.