Schematic overview of main determinants of immune–inflammatory–metabolic (IIM) homeostasis in health and disease. The diagram illustrates complex dynamic and toughly interconnected immune, inflammatory, and biochemical processes—the three main hallmarks of homeostasis. These evolutionary integrated processes (feedback loops) are regulated and influenced by numerous genetic, environmental, lifestyle, socioeconomic, age- and gender-related factors via myriads of signalling pathways. Analysis of individual IIM status provides a unified understanding of ageing, pathology, and progression of most chronic diseases and indicates the potential diagnostic, prognostic, preventive, and therapeutic targets.