Background and Objective: Obesity is a serious global health problem. In this study the effects of cumin extract in rats receiving high fat diets were investigated and compared with metformin. Materials and Methods: Eighty rats were divided into two sets of forty and each set was divided into four groups: the first group was a control group, the second group received a high fat diet, the third group received a high fat diet with metformin and forth group received a high fat diet with an extract of cumin. After treatment Malondialdehyde (MDA), catalase and antioxidant capacity (FRAP) were measured. Results: In the first set, the weight of the second group increased in comparison to the group receiving a normal diet. Weight in rats receiving metformin in combination with cumin extract decreased compared to the second group. MDA in rats belonging to the second group showed a greater increase compared to the control group, however FRAP was decreased. Results gathered from the second set are as follows: MDA increased in rats belonging to the second group more than the control group but, FRAP and catalase declined. MDA and catalase increased in the metformin group compared to the second group. PON1 activity, catalase and FRAP in cumin receiving rats increased compared to the second group and MDA declined. Conclusion: The results of the present study suggest that cumin extract has better protective effects against oxidative stress in high fat diet and obesity in comparison to metformin in rats