This review article discusses the role of metabolic regulation in the immune system in health and disease, focusing on immune cell metabolism and its impact on immune function. Metabolism, including glycolysis, oxidative phosphorylation, and fatty acid oxidation, influences immune cell phenotypes and functions. The concept of immunometabolism, introduced over a decade ago, has expanded to include metabolic reprogramming of immune cells in various diseases. Metabolic regulation of the immune system is crucial in the pathogenesis and progression of diseases such as cancer, autoimmune diseases, and metabolic diseases. The review explores the metabolic pathways and reprogramming in immune cells, including macrophages, T cells, B cells, and neutrophils, and how these pathways affect immune responses in different diseases. It also discusses the challenges of translating experimental results into clinical applications in immunometabolism. The review highlights the importance of understanding immune regulation in health and diseases to improve the management of most diseases. The article emphasizes the role of metabolic pathways in immune cell function, including glycometabolism, lipid metabolism, and amino acid metabolism, and how these pathways are altered in various diseases. It also discusses the impact of metabolites such as lactate and amino acids on immune cell function in cancer and other diseases. The review concludes that a better understanding of immune regulation in health and diseases will improve the management of most diseases.This review article discusses the role of metabolic regulation in the immune system in health and disease, focusing on immune cell metabolism and its impact on immune function. Metabolism, including glycolysis, oxidative phosphorylation, and fatty acid oxidation, influences immune cell phenotypes and functions. The concept of immunometabolism, introduced over a decade ago, has expanded to include metabolic reprogramming of immune cells in various diseases. Metabolic regulation of the immune system is crucial in the pathogenesis and progression of diseases such as cancer, autoimmune diseases, and metabolic diseases. The review explores the metabolic pathways and reprogramming in immune cells, including macrophages, T cells, B cells, and neutrophils, and how these pathways affect immune responses in different diseases. It also discusses the challenges of translating experimental results into clinical applications in immunometabolism. The review highlights the importance of understanding immune regulation in health and diseases to improve the management of most diseases. The article emphasizes the role of metabolic pathways in immune cell function, including glycometabolism, lipid metabolism, and amino acid metabolism, and how these pathways are altered in various diseases. It also discusses the impact of metabolites such as lactate and amino acids on immune cell function in cancer and other diseases. The review concludes that a better understanding of immune regulation in health and diseases will improve the management of most diseases.