The article reviews the significant role of obesity as a risk factor for various cancers, estimating that it contributes to approximately 20% of all cancer cases. The International Agency for Research into Cancer and the World Cancer Research Fund (WCRF) have identified endometrial, esophageal adenocarcinoma, colorectal, postmenopausal breast, prostate, and renal cancers as having the strongest associations with obesity. Other less common malignancies linked to obesity include leukemia, non-Hodgkin's lymphoma, multiple myeloma, malignant melanoma, and thyroid tumors. The review highlights several key factors that influence the increased cancer risk in obese individuals, including BMI, weight change, body fat distribution, diet, physical activity, insulin resistance, insulin-like growth factor-I (IGF-I), sex steroids, adipokines, chronic inflammation, oxidative stress, and immune function. It also discusses the potential mechanisms by which obesity promotes cancer development, such as hyperinsulinemia, IGF-I activity, sex hormone levels, and the production of proinflammatory molecules in adipose tissue. The article emphasizes the importance of understanding these underlying processes to develop novel methods for prevention and treatment. It concludes by noting that while the exact mechanisms are not fully understood, evidence from surgical interventions in obese patients suggests that weight management can significantly reduce cancer risk.The article reviews the significant role of obesity as a risk factor for various cancers, estimating that it contributes to approximately 20% of all cancer cases. The International Agency for Research into Cancer and the World Cancer Research Fund (WCRF) have identified endometrial, esophageal adenocarcinoma, colorectal, postmenopausal breast, prostate, and renal cancers as having the strongest associations with obesity. Other less common malignancies linked to obesity include leukemia, non-Hodgkin's lymphoma, multiple myeloma, malignant melanoma, and thyroid tumors. The review highlights several key factors that influence the increased cancer risk in obese individuals, including BMI, weight change, body fat distribution, diet, physical activity, insulin resistance, insulin-like growth factor-I (IGF-I), sex steroids, adipokines, chronic inflammation, oxidative stress, and immune function. It also discusses the potential mechanisms by which obesity promotes cancer development, such as hyperinsulinemia, IGF-I activity, sex hormone levels, and the production of proinflammatory molecules in adipose tissue. The article emphasizes the importance of understanding these underlying processes to develop novel methods for prevention and treatment. It concludes by noting that while the exact mechanisms are not fully understood, evidence from surgical interventions in obese patients suggests that weight management can significantly reduce cancer risk.