<p>Obesity is a common noncommunicable disease characterized by persistent low-grade chronic inflammation and is associated with various metabolic disturbances, including insulin resistance and diabetes. The search for effective obesity treatments has led to growing interest in the role of amino acids in metabolic regulation. Tryptophan (TRP), an essential amino acid, participates in several biological pathways, including the kynurenine, 5-hydroxytryptamine (5-HT, also known as serotonin), and indole pathways. Recent evidence underscores the significance of TRP metabolism in obesity, showing that various metabolites and enzymes in its metabolic pathways are altered in individuals with obesity. These changes influence physiological processes, mood regulation, and overall metabolic health. This review provides a comprehensive overview of TRP metabolism. It highlights the potential of targeting TRP metabolism as a therapeutic strategy for managing obesity and its related metabolic and psychological comorbidities.</p> Graphical Abstract <p></p>