Our genes are the conduit through which the environment communicates to the cells in our bodies. The responses to these signals include hormonal, metabolic and neurological changes to tissues and organs that manifest as phenotypes - measurable responses to gene transcription and translation. Thus, the health consequences of lifestyle behaviors such as physical activity, which can be broadly defined as 'environmental' exposures, are channeled through our genes. The extent to which these signals are conveyed depends in part on the structure and function of our genome. Hence, even when exposed to the same exercise regimes or doses of physical activity, responses vary markedly from one person to the next; some experience marked changes in disease phenotypes such as lipid and glucose concentrations, adiposity, or blood pressure levels, whilst others appear unresponsive. It is this process that underlies the concept that we will discuss in this chapter, a concept termed gene-lifestyle interaction. The aims of this chapter are (a) to convey to the reader the fundamental principles of gene-lifestyle interaction; (b) to describe the historical basis to this area of research; (c)to explain how understanding gene-lifestyle interactions might enhance our knowledge of the molecular mechanisms of disease; (d) to speculate on the ways in which information of gene-lifestyle interactions might eventually facilitate disease prevention, and (e) to overview the published literature which has focused on obesity as an outcome.
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