Metabolic diseases are the consequences of dysregulated metabolic pathways due to alterations in nutritional input, energy storage, release or dissipation, hormone response, cell signaling and/or the occurrence of genetic mutations. Lipids and lipid deriv- atives play important roles in all these processes. For instance, fatty acid (FA) species in nutritional oils act as taste molecules to signal their occurrence to the brain. The various FAs also exert alternate effects in cells, starting with enterocytes in which they affect the production of chylomicrons. The role of lipids as struc- tural species can be emphasized, particularly in membrane do- mains. FA storage in adipose tissue and their release on demand as well as their mitochondrial beta-oxidation are clearly key tar- gets for energetic alterations. The quality of FAs determines their bioavailability, their capacity to produce various bioactive lipids and their differential involvement as signaling intermediates. Last but not least, genetic mutations can impact enzyme reactions. In the current Biochimie special issue, expert researchers gather together their knowledge to give an overview of these various as- pects and to describe the more recent aspects of the influence of lipids in metabolic diseases.