Selected Dietary and Supplemental Phytochemicals in Adiposity-Based Chronic Disease: Molecular Mechanisms, Human Evidence, and Translational Gaps

Adiposity-based chronic disease (ABCD) encompasses the health consequences of excess or dysfunctional adipose tissue. Selected phytochemicals have been investigated as potential adjuncts, but experimental pathway activity does not establish clinical benefit. This narrative review examines quercetin, chlorogenic acids, epigallocatechin-3-gallate (EGCG), and berberine, with other interventions providing context. The evidence was supplemented by targeted PubMed searches through 27 October 2026 and appraised according to experimental model, formulation, exposure, clinical relevance, and safety. Published pooled body-weight differences were −0.35 kg (95% confidence interval, −2.03 to 1.33) for quercetin, −1.30 kg (−2.07 to −0.52) for selected green-coffee/chlorogenic-acid interventions, −0.74 kg (−0.97 to −0.51) for green-tea preparations, and −0.88 kg (−1.36 to −0.39) for berberine. These source-specific estimates are not head-to-head comparisons. A small crossover trial of quercetin reported reduced hepatic fat, whereas a six-month berberine trial found no significant benefit for visceral or hepatic fat. Coffee and green-tea findings do not isolate the effects of chlorogenic acid or EGCG. Most mechanistic evidence remains preclinical, and differences in chemical composition, circulating metabolites, administration, and outcome selection limit translation. The human-evidence-based selection also underrepresents less-studied phytochemicals; for the evaluated interventions, sustained adiposity reduction and patient-relevant benefit remain insufficiently established. Their potential role in comprehensive ABCD care requires product-specific assessment of efficacy, exposure, adverse effects, and interactions.