Background and Objectives: Obesity is linked to metabolic diseases characterized by insulin resistance, such as diabetes and cardiovascular disease. In this study, we investigated the metabolic disorders of uncomplicated obesity to identify early alterations in biological systems. Methods and Study Design: Metabolic differences between overweight/obese (n=36) and normal-weight (n=35) young Chinese men without known metabolic disorders were assessed. Metabolic profiling of the serum and urine was performed using ultra-performance liquid-chromatography quadrupole-time-of-flight mass spectrometry (UPLC-Q-TOF-MS). Partial least squares discriminant analysis (PLS-DA) was undertaken to reveal and classify the differences between the two groups. Results: Compared to normal-weight men, obese men had higher levels of the serum metabolites phenylalanine, Phe-Phe, and L-tryptophan, whereas those of p-cresol sulfate and p-cresol were less in obesity. Urinary metabolites phenylacetamide, L-glutamine, phenylacetylglutamine, indoxyl sulfate, p-cresol, and p-cresol sulfate were greater in obese men. Conclusions: These findings indicate that disorders involving aromatic amino acids and the tricarboxylic acid cycle (TCA) have microbiomic involvement in the uncomplicated phase of obesity.