The two main mechanisms that lead to the breakdown of lipid granules are lipolysis and lipophagy. 

1. Lipolysis occurs in the adipose tissue. In this process, lipid granules are broken down by hydrolysis into their two main components – glycerol and fatty acids. 
2. Lipophagy involves the selective autophagic degradation of intracellular lipid granules, which are the main lipid storage organelles in eukaryotic cells.