A composition comprising extracts containing oil palm phenolics in an amount effective for use in a method of reducing cholesterol biosynthesis and thus preventing obesity. The composition up regulates fatty acid beta oxidation and down regulates cholesterol biosynthesis in livers. The composition is useful for prevention of obesity associated diseases. The composition delays the onset of obesity and attenuates the inflammatory response of atherogenic diet, whereby the composition aids to suppress the inflammatory response thereby ameliorating artherosclerosis. The composition delays weight gain or obesity thereby preventing the effects of dyslipidemia.