Abstract
China’s dietary transition has diversified food consumption, but the resulting carbon pressure may arise from either greater food quantity or a more carbon-intensive composition. Prior studies have estimated dietary footprints, socioeconomic drivers, or optimized sustainable diets, but have seldom separated these two ex-post channels within a recent, harmonized provincial urban–rural panel. Using data for 31 provinces from 2015 to 2024, this study constructs a fixed-coefficient Dietary-Structure Carbon Pressure Index (DSCPI) for overall, urban, and rural residents and decomposes its change into quantity and structure effects. We further conduct population-weighted and energy-based sensitivity decompositions to assess whether the diagnosis depends on provincial weighting or on defining quantity in kilograms. Unweighted provincial-average DSCPI increased by 13.1% overall, 8.1% for urban residents, and 23.4% for rural residents. In the kilogram-based decomposition, structure change accounted for 44.0%, 49.1%, and 36.3% of the respective increases; the rural structure effect was nevertheless larger in absolute magnitude than the urban effect. Population weighting strengthened the estimated increases to 18.0, 11.2, and 26.7% and preserved positive quantity and structure effects. When quantity was redefined as dietary energy, however, the structure effect became dominant: the energy-quantity effect was negative for the overall and urban samples and only modestly positive for the rural sample. The most robust finding is therefore that dietary upgrading increased fixed-coefficient structural carbon pressure and that compositional change contributed positively in every resident group. The relative division between quantity and structure is measurement-dependent, so policy should combine nutrition-compatible food-loss and waste reduction with guidance toward lower-carbon dietary composition rather than treating either channel as sufficient on its own.