The main concern in exploring modulation of PPARs in experimental animals is probably the choice of the model. Although mechanistic studies may be well designed using knockout and transgenic animals, the interpretation of results with respect to inferred results of PPAR activation into humans should be performed cautiously. This is even more important in this field considering that undesired and unexpected effects have been already described in human epidemiologic studies. Taken together, these observations suggest that a global approach using omic technologies, although expensive, is probably the most suitable to obtain useful data. Also, in this approach, we propose all tissues should be explored, not only those obviously relevant to metabolism, or stored in proper conditions if further assessment is required.