BACKGROUND: Adipose tissue produces and releases a variety of proinflammatory cytokines. The aim of this study was to investigate whether proinflammatory cytokines are increased and insulin resistance is presented in nonobese women with high body fat and low fat free mass. METHODS: Sixty nonobese adult premenopausal women (body mass index, BMI < 25 kg/m2) were included in this study. Body composition was determined by dual energy absoprtiometry (DXA). Fasting glucose, lipid profiles, tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), C reactive protein (CRP) and basal insulin were measured. RESULTS: The subjects with high body fat (> or = 30%) had higher CRP levels (P = 0.024), IL-6 levels (P = 0.008), insulin levels (P = 0.003), and homeostasis model assessment-IR (HOMA-IR) (P = 0.020) than those of the subjects with low body fat. In a subset of 32 subjects with high body fat (> or = 30%), the number of subjects with high fat free mass index (FFMI) (> or = 13.5 kg/m2) had higher atherogenic index than that of subjects with low FFMI (FFMI < 13.5 kg/m2) (P < 0.05). IL-6 was correlated with % body fat, fat mass index (FMI), and fat mass (P < 0.05). HOMA-IR was correlated with % body fat and FMI (P < 0.05). To investigate predictors of cytokines and HOMA-IR, multiple regression analysis was used. % body fat was a predictor for IL-6 and, while age and % body fat were predictors of HOMA-IR in study subjects. Conclusions: This study suggests that insulin resistance may be present in nonobese women with high body fat and low fat free mass.