Ecological physiology aims to understand how organisms function in and respond to their natural environment, including periods that might be stressful. Examining how individuals respond to different conditions provides an indication of how species and populations survive and how they might persist under global change. Using large carnivores in a desert environment as a model system, we explore the physiological and morphological responses to inhabiting harsh conditions. Large carnivores are interesting model organisms because they are physiologically adapted to chase, capture and subdue prey. This process is unpredictable, often resulting in failure, and also may be energetically costly especially when prey are sparsely distributed. In addition, many of the environments where these species occur are particularly sensitive to global change, and so individuals may also have to deal with aspects such as increasing aridity and avoidance of hyperthermia. We examined energy expenditure, heat production and foraging behaviours in Kalahari cheetahs to assess whether and how environmental constraints might limit their viability.