Physical activity in context: the systems and inequalities of metabolic harm.

Physical inactivity and sedentary lifestyles are now accepted as major contributors to metabolic harm and disorder in the 21st century. These harms are frequently framed as a result of individual choices, with solutions leaning into personal responsibility. There are, however, crucial structural influences on individuals' capacity to engage with so-called lifestyle advice. In particular, the way in which structural environments influence labour, lives, and communities can present several barriers to exercise and physical activity. These pressures, and their consequences, have particular and compounding effects on those who are economically and socially marginalised. When scientific and clinical literature overlooks these structural determinants of lifestyle, the effectiveness of interventions are undermined, or even worse, intervention failure reinforces judgement and isolation, which cements metabolically harmful behaviours. In this Viewpoint, we call for renewed focus on how social structures influence physical activity to characterise the injustices underpinning current metabolic health and harm.