Rodents respond to chronic high fat diet in at least two ways: some of them may readily gain body weight and become obese (termed obesity-prone, OP), and others may not (termed obesity-resistant, OR). Transcriptomic and metabonomic profiling of OP and OR rats has been conducted, showing two sets of significantly different phenotypic profiles in response to 16 weeks of high fat diet. We observed significant differences in transcriptional expression of nearly 80 genes, some of which are known to be involved in lipid metabolism, transport, and ketone body production. The different metabolic profiles in liver tissue extracts, serum, and urine between the two phenotypes can be ascribed to the corresponding pathways identified with multivariate statistical analysis, including fatty acid metabolism, Krebs cycle, and amino acid metabolism. The integration of results from transcriptomic and metabonomic studies revealed that the altered metabolic pathways in OP rats may involve the increased activity of sympathetic nervous system and Krebs cycle, an increased production of ketone bodies, and an adaptive regulatory process to store excessive lipids in liver through reverse cholesterol transport process. These biochemical variations at transcriptional and metabolic levels as a result of dietary intervention highlight the significance of combined "omics" strategy in the mechanistic study of obesity and metabolic disorders.