A warming climate is among the most consequential societal changes currently underway, and its implications for obesity are bidirectional. In Australia, nine of the ten hottest years on record have occurred since 2005, and summer conditions previously classified as “extreme” are projected to become increasingly typical within the next decade. Rising ambient temperatures represent an emerging, yet largely unquantified, constraint on physical activity, with potential downstream effects on sleep, behaviour, and energy balance that remain insufficiently characterised.
People living with obesity are also consistently identified as heat-vulnerable; however, the mechanistic basis of this vulnerability is often misattributed. In this presentation, I will outline the determinants of an individual’s capacity to dissipate heat, explain why body size, metabolic heat production, and comorbidities may be more important than adiposity per se, and examine how commonly prescribed medications, housing quality, and the built environment interact to compound heat exposure and risk.
Drawing on research from the Heat and Health Research Centre at the University of Sydney, which investigates heat vulnerability and potential mitigation strategies across early life, working life, and later life, I will illustrate these concepts using selected examples from our laboratory, field, and population-based studies. I will conclude by considering the practical implications for clinicians, including patient guidance on physical activity, hydration, and cooling during hot weather, and by identifying key evidence gaps, particularly regarding rapid pharmacologically induced weight loss and its potential effects on thermoregulation and fluid balance.