This review reframes urban metabolism at the scale of interconnected cities and regions. It argues that the metabolism of one city cannot be understood independently of neighbouring settlements, infrastructures and territories that provide resources, absorb wastes or share services.

The authors analyse seventy-four peer-reviewed studies and organise the literature according to metabolic capacity, requirements and urban characteristics. They also identify integrated, networked and combined methodological traditions. The proposed interconnected urban matrix brings these dimensions together and highlights the need for spatially explicit analysis of linkages and dependencies.

The framework is particularly relevant to smaller cities, which are often overlooked in metropolitan research despite their central role in regional transition. It provides the conceptual basis for ReFrameCity and for comparative work on metabolic geographies.