Regulation of Adipose Tissue Metabolism During Fasting

There is widespread interest in fasting as a therapeutic or preventive regimen for improving health. This review provides an overview of the impact of fasting on adipose tissue metabolism, with special attention to sexually dimorphic regulation. During fasting, the storage of triacylglycerols in adipose tissue is inhibited via suppression of the extracellular lipolytic enzyme lipoprotein lipase. By contrast, the breakdown of stored triacylglycerols and subsequent release of fatty acids and glycerol in the blood are enhanced via stimulation of the intracellular lipolytic enzymes adipose triglyceride lipase and hormone-sensitive lipase. These metabolic alterations are driven by changes in humoral factors such as insulin, glucagon, corticosteroids, growth hormone, and catecholamines, as well as by neuronal pathways, and are mediated by transcriptional and posttranscriptional regulation of critical enzymes. Overall, fasting profoundly influences adipose tissue metabolism and leads to mobilization of stored triacylglycerols and the repartitioning of circulating triacylglycerols to nonadipose tissues.