The purpose of this review has been to investigate the potential preventive effects of polyphenols on obesity, focusing on their effects on fat cells and their ability to regulate fat metabolism and intestinal flora and exploring their relationship with obesity-related signaling pathways from an obesity prevention perspective—for example, increasing BAT activity, increasing protein factors that regulate brown fat thermogenesis, increasing thermogenesis, regulating the Rb pathway, P38/MAPK pathway, Wnt signaling pathway, and transcription factor regulation to inhibit adipogenesis. The gene discussed is MAPK14; the disease is obesity due to melanocortin 4 receptor deficiency.