Background & objectives: It is well-established that diet composition can have a direct impact on normal physiological functions, as well as on pathological conditions such as obesity, diabetes, and cardiovascular disease. Therefore, this study was designed to investigate the effect of 4 weeks' different feeding programs comparing body weight, food intake, lipid profiles, serum glucose, insulin and leptin. In addition, we evaluated the oxidative state and the histological appearance of the liver. Methods: Twenty four male albino rats were fed with high fat diet (HFD), high sucrose diet (HSD), and high starch diet (HTD) for a period of 4 weeks compared with a control diet (CD) group of equal caloric values. Results: Rats fed the different experimental diets showed dyslipidemia, hyperleptinemia, hyperglycemia, hyperinsulinemia and alteration of oxidative markers and histological changes in the hepatic tissues (steatosis, micro and macrovacuolation, inflammatory cell infiltration and focal necrosis in different zones). HSD showed the severest changes while HTC the least. HSD decreased the final daily food intake, body weight (BW) and body mass index (BMI), while HFD increased at first then decreased finally daily food intake in spite of increased final BW and BMI. HTC decreased final BW and BMI in spite of increased food intake. Conclusion Improper selection of diet macronutrients is more serious than excess caloric intake especially for obese or those with hepatic or other organ challenges. High fat diet has deleterious metabolic effects. The type of carbohydrate is also a determinant factor; complex carbohydrates (starch) being less hazardous than simple ones (sucrose).