Summary:- In general, Deoxyribonucleic acid (DNA) contains the genetic information, used in the development and functioning of living organisms. It is often called as a blueprint, since it contains the genetic information, from which the components of celObesity represents a disruption in balancing fuel intake with energy expenditure in favor of energy conservation. Adiposity is known to be carefully regulated and, over time, highly resistant to major changes, raising questions about how energy homeostasiThis work aim to study:Effect of obesity on gene expression of tissue DNAEffect of obesity on anti oxidants. For this our search aimed to study the effect of obesity through feeding high caloric diet with high fat content on tissue genes expression in liver and muscle and compare it with the same genes in low caloric diet try Fifty male Albino rats were used in the study. Their weight ranged from 120 gm .Rats will be housed in stainless steel cages in the laboratory house in biochemistry department which will adapted to the room and cage environment 7 day before the beginning The result of the study can be summarized as follows:1- Effect of obesity and conjugated linoleic acid (CLA) treatment on Body weight:There is highly significant increase in the body weight of obese group in comparison with its control one that considered indication of obesity occurrence, but significantly decrease in conjugated linoleic acid(CLA) treatment which treated with conjugated2- Effect of obesity and conjugated linoleic acid (CLA) treatment on lipid profile:We measured lipid profile for obesity indication. there is very high significant increased in the concentration of total lipid ,total cholesterol, triglycerides ,LDL and VLDL in obese group in comparison with its control ,but significantly decreased of HD3- Effect of obesity and conjugated linoleic acid (CLA) treatment on catalase (CAT) activity in kidney homogenate:There is significant decrease in the activity of catalase in obese group than control one but increase in Conjugated linoleic acid (CLA) treatment than control.4- Effect of obesity and conjugated linoleic acid (CLA) treatment on catalase(CAT) activity in muscle:There is significant decrease in the activity of catalase in obese group than control one but increase in Conjugated linoleic acid (CLA) treatment than control.5- Effect of obesity and conjugated linoleic acid (CLA) treatment on catalase(CAT) activity in liver homogenate:There is significant decrease in the activity of catalase in obese group than control one but increase in Conjugated linoleic acid (CLA) treatment than control.