The aim of the study was to investigate the improving effect of Garcinia cambogia extract on performance metrics, and serum non-esterified fatty acids (NEFA) and C-reactive protein (CRP) levels in rats fed with atherogenic diet. Thirty, one-year-old, female Sprague-Dawley rats were randomly assigned to three experimental groups of ten animals each. Control group was fed with basal diet (2% liquid vegetable oil, 0% cholesterol), while the diets of groups 2 and 3 contained vegetable oil (2% liquid- and 5% hydrogenated-vegetable oil) and cholesterol (3%). 4.5% Garcinia cambogia was added to the diet of group 3 from day 45. Performance metrics were significantly lower in group 3 than the other groups. Serum NEFA levels were significantly higher in group 3 than the control group on day 45, and in group 3 compared with the other groups on day 75. Serum CRP levels were not significantly different among all groups in all days. In conclusion, the reduced performance metrics indicate that supplementation with Garcinia cambogia extract is a novel therapeutic tool for weight management. Also, this study indicates that large doses of Garcinia cambogia can lead to a substantial increase in serum NEFA concentrations which may be due to the increased fat degradation.