Advances in Research

Obesity is increasingly conceptualised not as a disorder of body size but as a chronic condition of adipose tissue function with consequences that extend across almost every organ system. Cardiometabolic and oncological sequelae dominate the literature, whereas the dermatological, ophthalmological and gastrointestinal consequences are usually examined within separate specialty silos, each with its own outcome definitions, exposure measures and explanatory models. This critical narrative review evaluates whether these three organ systems share a common pathophysiological substrate, here termed the metabolic axis, and whether the evidence supporting that shared substrate is strong enough to justify integrated clinical reasoning. Literature was identified through structured searching of a federated biomedical index with bibliographic verification through a metadata registry, complemented by targeted retrieval of consensus statements and landmark trials. Evidence was appraised for design adequacy, exposure characterisation, confounding control and consistency rather than pooled quantitatively. Four mediators recur across systems: adipose tissue expansion with extracellular matrix remodelling and hypoxia; insulin resistance with compensatory hyperinsulinaemia and altered growth-factor signalling; chronic low-grade inflammation with reprogramming of tissue-resident immune populations; and gut microbial and barrier alterations feeding into hepatic and systemic metabolism. Support for these mediators is strongest where an intermediate phenotype can be measured directly, as in acanthosis nigricans, steatotic liver disease and idiopathic intracranial hypertension, and weakest where associations rest on body mass index alone, as in glaucoma, cataract and age-related macular degeneration. Weight-loss interventions provide the most informative natural experiment, yet outcomes diverge markedly between systems, with intracranial pressure and hepatic histology responding favourably while reflux, gallstone formation and early diabetic retinopathy show neutral or adverse short-term trajectories. Divergence of this kind constrains any simple claim that adiposity reduction uniformly reverses obesity-associated organ injury. Priorities include replacing body mass index with compartment-specific adiposity measures, harmonising outcome definitions across specialties, and designing weight-loss trials that capture dermatological, ocular and luminal endpoints prospectively.