Can i take a fat burner supplement or do a basic cardio while taking isotritinion?

Yes: I know you've got some pretty severe drug restrictions with isotretinoin--but you should not have problems with an herbal "fat burner"--although frankly, they don't do much good. I recommend Metformin, to restore insulin receptor sensitivity, to help you lose weight. Also, white kidney bean extract taken with carbohydrates (when you "fall of the wagon") acts as a "starch blocker."