Background: Childhood obesity can cause the development of cardiovascular risk factors. We assessed the effect of a multidisciplinary intervention program on cardiovascular risk factors and compared this effect with a usual-care program in 3-to 5-y-old overweight or obese children. Methods: Seventy-five children were randomly assigned to a multidisciplinary intervention or a usual-care program. Anthropometry, body composition, and abdominal adipose tissue were assessed at the start and end of a 16-wk program. Concurrently, fasting concentrations of serum lipids, glucose, insulin, HbA1c, leptin, adiponectin, high-sensitive C-reactive protein (hsCRP), tumor necrosis factor (TNF)-α, and interleukin (IL)-6 were determined. results: In both groups, insulin sensitivity improved, demonstrated by decreased insulin concentrations and a decreased HOMA2-IR. In the multidisciplinary intervention group, there was also a decrease of HbA1c and TNF-α. In the usual-care group, an increase in glucose concentrations was found. Comparing both groups, changes over time were not different, besides trends in the decrease in total cholesterol and TNF-α, in favor of the multidisciplinary intervention group. Combining the results of both groups, a correlation was found between the decrease in body fat percentage (BF%), and both HOMA2-IR and triglyceride (TG) concentrations. conclusion: In 3-to 5-y-old children, both obesity intervention programs improved insulin sensitivity, in parallel with a reduced BF%. r ecent data have shown that the prevalence of childhood overweight and obesity in the Netherlands is still increasing (1). Childhood obesity is a risk factor for the development of insulin resistance (IR), dyslipidemia, and hypertension at a later age, together described as metabolic syndrome (MS) (2). MS cannot be diagnosed in children under the age of 10 y (3). However, increased concentrations of the separate components of MS have already been demonstrated in children aged 6-9 y (4).Systemic low-grade inflammation may be an underlying cause of MS, induced by the release of inflammatory cytokines from adipose tissue, and even more so from visceral adipose tissue (5,6). Increased concentrations of tumor necrosis factor (TNF)-α, high-sensitive C-reactive protein (hsCRP), and interleukin (IL)-6 have been found in obese children aged 9-13 y (7,8). The adipose tissue hormone adiponectin has anti-inflammatory properties, demonstrated by the significant inverse correlation with markers of inflammation in obese children (8). Whether these deleterious processes related to obesity are already present in overweight and obesity at a very young age is unknown, and no data on systemic low-grade inflammation are available in very young obese children.Multidisciplinary lifestyle intervention programs for obese children have proven to be successful in reducing weight (9). Recent studies demonstrated that weight loss in obese children aged 6-11 y also reduced low-grade inflammation and IR (4,8). In obese children, 9-13 y old, weight loss over a 1-y p...