Asymmetrical resource behaviors shape key leverage points for sustainability synergies and trade-offs across China’s food supply chain

<h2>Summary</h2> Ensuring global food security requires understanding fine-scale sustainability trade-offs and synergies within food supply chains (FSCs). Here, we develop a supernetwork framework that refines analysis to detailed FSC activities by incorporating China's 92 region-sector-product nodes to diagnose resource consumption, efficiency dynamics, and systemic interactions. The analysis shows pronounced asymmetries in resource behaviors across China's FSCs. By 2050, 87.10%–96.77% of regions will rely on planetary boundary transgressions for water or land use to meet food demands. The most resource-intensive 1% of activities, typically western pork production and coastal soybean trade, drive a disproportionate 12.24%–20.23% of water and 28.19%–31.03% of land consumption, exposing critical FSC vulnerabilities. Downstream efficiency gains enhance food accessibility but simultaneously intensify water-land consumption and systemic risks. Yet, midstream activities offer overlooked synergetic potential, achieving robust efficiency improvements (132.79%–177.18%) independent of resource use. These granular insights identify localized, actionable leverage points to realign FSC sustainability trajectories.