The objective of the study is to assess the effect of two diets with different fat composition on cholesterol metabolism. The study was a randomized cross-over trial where volunteers follow two study periods with different types of meat (lean and fat red meat) separately by a ten days wash-out period. At the beginning of the study and after the study periods the following parameters are determined: anthropometric (weight, waist, circumference and body mass index), blood pressure, dietary (72-hours dietary registry) and exercise assessments and biochemical analysis (total cholesterol, triglycerides, HDL cholesterol, LDL cholesterol, apolipoprotein A1, apolipoprotein B, iron, transferring, ferritin, uric acid, glucose, HbA1c and insulin). Serum concentration of non cholesterol sterols (sitosterol, campesterol, stigmasterol, desmosterol and lanosterol) and oxysterols (24S-hydroxycholesterol, 27-hydroxycholesterol and 7α-hydroxycholestenone) were measured by High Performance Liquid Chromatography tandem Mass Spectrometry in these subjects throughout along the study in order to demonstrate the effect of different red meat on the hepatic metabolism of cholesterol.