Peptide YY (PYY) is a gut-derived peptide hormone primarily synthesized and secreted by the L-cells in the ileum and colon. It is a 36-amino acid peptide that exists in two major forms: PYY1-36 and PYY3-36, with the latter being the more biologically active form. PYY is released postprandially in proportion to caloric intake and plays a significant role in regulating appetite and energy homeostasis. Researchers have extensively studied PYY in the context of metabolic disorders, particularly obesity and type 2 diabetes. It has been observed to reduce food intake and promote satiety, making it a potential therapeutic target for weight management. Additionally, PYY has been implicated in modulating insulin secretion and glucose homeostasis. The mechanism of action of PYY involves binding to the neuropeptide Y (NPY) receptors, particularly the Y2 receptor, which is predominantly expressed in the hypothalamus and other regions of the brain involved in appetite regulation. This interaction inhibits the release of neuropeptide Y, a potent orexigenic peptide, thereby reducing hunger signals. Pharmacokinetically, PYY has a relatively short half-life, with researchers noting rapid degradation by dipeptidyl peptidase-IV (DPP-IV). The bioavailability of PYY varies by administration route, with subcutaneous and intravenous routes being more effective than oral administration due to poor gastrointestinal stability. Current research on PYY is focused on its potential as a therapeutic agent for obesity and metabolic syndrome. However, it is not yet approved as a medicinal product by major regulatory agencies, and its use is primarily confined to research settings.