The Human Genome Project and rapid advances in high-throughput molecular technologies are providing an unprecedented opportunity to advance the understanding of the common polygenic diet-related diseases, including obesity, the metabolic syndrome, type 2 diabetes mellitus, CVD and some cancers. In particular, transcriptomic approaches that allow multiple simultaneous gene-expression profiles facilitate the characterisation of metabolic perturbations that underlie diet-related pathologies. The present paper will focus on 'transcriptomic signatures' to characterise and understand the molecular mechanisms that accurately reflect 'metabolic health'.