INS and obesity due to melanocortin 4 receptor deficiency: In addition, metabolomics has been increasingly applied to the biomarker discovery of cardiovascular diseases, diabetes, and early changes of metabolites in obesity through metabolic profiling in patients with metabolic syndrome[7-9], MS-based metabolic profiling of acylcarnitines species in insulin resistance animal models[10], cellular lipid signaling[11], as well as profiling amino acids and acylcarnitines in obesity individuals[12].