This review will focus on the recent findings in adipose tissue metabolism with special attention to human adipocyte biology and physiology. There are major advances stemming from the concomitant results obtained from studies on mature human adipocytes, human preadipocytes differentiated in vitro and murine adipose cell lines. Physiological developments have been based on the expanded utilization of various kinds of murine transgenic models and physiological techniques such as microdialysis, open-flow microperfusion, arteriovenous techniques and the utilization of deuterium- or tritium-labelled metabolites that have provided a number of physiological advances in the understanding of human adipose tissue physiology. Gene expression profiling studies and nutrigenomics are emerging methods that herald interesting approaches for the future. An overview of recent discoveries in the mechanisms involved in the control of free fatty acid uptake, triacylglycerol synthesis and fat deposition will be discussed, as well as recent advances in the mechanisms involved in the lipolytic pathways, the role of lipases and perilipins. In addition, the in vivo validation of catecholamine action and the discovery of the lipolytic effects of natriuretic peptides will also be covered.