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Background: Visceral obesity is increasingly recognised not as a simple excess of adipose tissue, but as a systemic pathological condition characterised by profound metabolic, endocrine, and immune dysregulation. Visceral adipose tissue (VAT) operates as an autonomous neuro-immune-endocrine organ whose dysfunctional expansion drives insulin resistance, atherogenesis, and accelerated cellular ageing through mechanisms converging on chronic low-grade sterile inflammation, referred to as inflammaging. Objectives: This narrative review integrates evidence across four domains: (1) the multi-system clinical complications of visceral obesity and the methodological controversies surrounding its measurement; (2) the cellular heterogeneity, immunometabolic reprogramming, and molecular mechanisms through which excess VAT accelerates biological ageing, with a focus on genomic instability, mitochondrial dysfunction, the NAD⁺/sirtuin regulatory axis, cellular senescence, and inter-organ communication; (3) the role of bioelectrical impedance analysis (BIA)—particularly phase angle—as a non-invasive functional biomarker of biological age and longevity, positioned critically against alternative assessment methods; and (4) current knowledge gaps and priorities for future research. Methods: A narrative review of PubMed/MEDLINE, Google Scholar, and the Cochrane Library was conducted using MeSH terms and free-text keywords including visceral obesity, bioelectrical impedance analysis, phase angle, sarcopenia, inflammaging, mitochondrial dysfunction, cellular senescence, epigenetic clocks, NAD⁺, sirtuin, and longevity, supplemented by citation-tracking of retrieved reviews. English-language articles published up to April 2025 were considered, prioritising systematic reviews, meta-analyses, and prospective cohort studies; formal risk-of-bias tools and quantitative synthesis were not applied, consistent with a narrative review design. Results and Discussion: BIA-derived phase angle constitutes a macroscopic electrobiological correlate of inflammaging: low phase angle values in visceral obese subjects overlap with those of frail elderly individuals, reflecting impaired membrane integrity, loss of active cell mass, and altered ICW/ECW balance. However, this evidence base remains largely cross-sectional and correlative; the directionality and population-specific calibration of BIA-derived indices constitute the principal unresolved methodological questions. Integration with epigenetic clocks, circulating NAD⁺ levels, and gut microbiome indices offers a framework for dynamic biological age assessment, though prospective interventional validation is still lacking. Sarcopenic obesity, evaluated through EWGSOP2 combined with BIA-derived skeletal muscle mass index and handgrip dynamometry, represents a critical comorbidity demanding integrated therapeutic targeting. Conclusions: BIA provides a quantitative, accessible correlate for translating cellular metabolic health into clinically actionable parameters, complementary to rather than a replacement for anthropometric and imaging-based methods. Optimising phase angle and reducing VAT through anti-inflammatory nutrition, exercise, and nutraceutical strategies targeting the NAD⁺/sirtuin and mTOR/AMPK axes constitutes a measurable objective for the promotion of healthy longevity, contingent on the longitudinal, mechanistic studies identified as priorities in this review. Full article

In recent years, the bidirectional regulatory mechanism of the bone-brain axis has become a hotspot for interdisciplinary research. In this paper, we systematically review the anatomical and functional links between bone and the central nervous system, focusing on the regulation of brain function by bone-derived signals and their clinical translational potential. At the anatomical level, the blood–brain barrier permeability mechanism and the unique structure of the periventricular organs establish the anatomical basis for bone-brain information transmission. Innovative discoveries indicate that the bone cell network (bone marrow mesenchymal stem cells, osteoblasts, osteoclasts, and bone marrow monocytes) directly regulates neuroplasticity and the inflammatory microenvironment through the secretion of factors such as osteocalcin, lipid transporter protein 2, nuclear factor κB receptor-activating factor ligand, and fibroblast growth factor 23, as well as exosome-mediated remote signaling. Clinical studies have revealed a bidirectional vicious cycle between osteoporosis and Alzheimer’s disease: reduced bone density exacerbates Alzheimer’s disease pathology through pathways such as PDGF-BB, while AD-related neurodegeneration further accelerates bone loss. The breakthrough lies in the discovery that anti-osteoporotic drugs, such as bisphosphonates, improve cognitive function. In contrast, neuroactive drugs modulate bone metabolism, providing new strategies for the treatment of comorbid conditions. Additionally, whole-body vibration therapy shows potential for non-pharmacological interventions by modulating bone-brain interactions through the mechano-osteoclast signaling axis. In the future, it will be essential to integrate multiple groups of biomarkers to develop early diagnostic tools that promote precise prevention and treatment of bone-brain comorbidities. This article provides a new perspective on the mechanisms and therapeutic strategies of neuroskeletal comorbidities. Full article