Media representation of health and illness is a common pursuit of discourse analysts. Less common is the study of how healthcare professionals and researchers provide explanations about health and disease in interview situations. In this paper we focus on professional explanations concerning Type 2 Diabetes and Coronary Heart Disease which are major health problems in the Western world, consuming a significant percentage of the health budget in many countries. Efforts to halt the increasing incidence are directed, in part, to understanding the causes of both illnesses. As part of a larger project aimed at understanding causal explanations for these conditions, we interviewed 18 clinicians and researchers working in the field in the UK to determine their views on why the incidence of these conditions continues to rise worldwide. We adopt a rhetorical discourse analytic perspective to highlight the function and significance of raising these issues as causal explanations. While scientific physiological and epidemiological explanations reflecting current research featured in the interviewees’ accounts, of greater interest were the explanations of socioeconomic and political factors that contribute to the ongoing epidemic through the mediating physiological processes.