During the last two decades, numerous efforts have been made to identify reliable and predictive noninvasive biomarkers to detect the early signs of metabolic disorders due to deregulation of lipid and glucose homeostasis. Several studies demonstrate that miRNAs--small noncoding RNAs involved in the regulation of gene expression--may play crucial roles in the control of metabolism. Alterations of miRNA levels often occur in metabolic disorders, both in specific tissues and plasma. Therefore, it is conceivable that the analysis of circulating miRNA profiles may improve not only the knowledge of miRNA-mediated mechanisms and effects in metabolism, but may also offer an alternative diagnostic tool. In the first part of this review we provide an overview of miRNA biogenesis and regulation, and experimental approaches for studying their expression levels. Afterwards, we discuss recent data regarding altered intracellular and circulating miRNAs associated with specific metabolic disorders.