Aim of this study was to investigate effects of high fat diet on rat liver and weight gain. By this purpose 30 Wistar Albino rats were divided into 4 groups. 1. High carbonhydrate diet group for 16 weeks (K16), 2. High fatty diet group for 16 weeks (D16), 3. High carbonhydrate diet group 20 weeks (K20), 4. High fatty diet group 20 weeks (D20). High fatty diet; % 60 fat (1/3 canola, 1/3margarine, 1/3 sunflower oil), % 20 protein, % 20 carbohydrate and high carbohydrate control diet; % 69 carbohydrate, % 20 protein and % 11 margarine was composed. There weren't any significant differences between groups as compared to body weight, liver weight and epididymal fat weight. At the result of biochemical analysis, LDH in 16 weeks high carbohydrate diet and ALT in 20 weeks high carbonhydrate diet was significant higher than high fatty diet groups. In histological research, even though fibrosis, inflamation, steatosis findings observed at portal area of all groups, there wasn't significant statistical differences. Similar to this, a-SMA and TGF-beta accumulation in all groups were similar interms of immunohistological investigation. In conclusion; this study showed that comparing to relatively high fatty diet rich with omega-9, high carbonhydrate feeding caused liver injury and anointment and there wasn't significant differences in terms of weight gain. By this way, we think that decreasing of carbonhydrate and increasing amount of olive oil, canola oil and hazelnut oil at which containing omega-9 in diet, liver can be protected.