The new scientific field of nutrigenomics utilizes genomic tools, like microarrays, to analyze metabolic adaptations induced by variations in nutritional status. Here we describe how transcriptional regulation patterns caused by nutritional changes can be identified using gene expression profiling. This includes technical remarks on microarray analysis and data processing, as well as giving biological meaning to statistically solid data. We highlight our recent findings of transcriptional regulation of genes representing specific signaling and metabolic pathways in mouse liver under starvation. The results show strong correlations to previously identified responses to caloric restriction, which can be linked to lifespan extension.