Abstract：The theory of "excessive intake of rich and greasy food leads to severe carbuncle，" originating from Su Wen · Sheng Qi Tong Tian Lun （Plain Questions · Treatise on the Communication of Vital Qi with Heaven）， is a foundational classical exposition of the dietary etiological theory in traditional Chinese medicine （TCM）. Tracing back to this classical theory and integrating the academic thought of "diet toxin-induced ulceration" theory proposed by Professor DONG Mingguo， a renowned TCM practitioner of Guangdong Province， this paper systematically explores its theoretical relevance to ulcerative colitis （UC）. TCM holds that the pathological progression of internal retention of damp-heat，qi and blood stasis stagnation，and flesh rotting into carbuncle resulting from excessive intake of greasy， sweet， and rich diets closely aligns with the core pathogenesis of UC as an "internal carbuncle." The "diet toxin， " generated from the impaired transportation and transformation function of the spleen and stomach in processing rich and greasy foods，serves as the central pathological pivotal point throughout the onset，progression，and recurrence of UC. On this basis，this paper proposes a four-stage dynamic pathogenesis system for UC：the pre-disease stage （internal retention of damp-heat， emergence of diet toxin）， the active stage （accumulation of diet toxin， transformation of turbidity and toxins into heat），the protracted stage（ spleen deficiency and lingering toxin，intermingled deficiency and excess）， and the post-convalescence stage （impairment of spleen and kidney， incomplete elimination of toxin）.Correspondingly，stage-specific treatment strategies of eliminating，expulsing，and tonifying are proposed，aiming to provide new references for the clinical management of UC from the perspective of diet toxin theory.