Model of adipose tissue cellularity dynamics during food restriction.

Adipose tissue and adipocytes play a central role in the pathogenesis of metabolic diseases related to obesity. Size of fat cells depends on the balance of synthesis and mobilization of lipids and can undergo important variations throughout the life of the organism. These variations usually occur when storing and releasing lipids according to energy demand. In particular when confronted to severe food restriction, adipocyte releases its lipid content via a process called lipolysis. We propose a mathematical model that combines cell diameter distribution and lipolytic response to show that lipid release is a surface (radius squared) limited mechanism. Since this size-dependent rate affects the cell׳s shrinkage speed, we are able to predict the cell size distribution evolution when lipolysis is the only factor at work: such as during an important food restriction. Performing recurrent surgical biopsies on rats, we measured the evolution of adipose cell size distribution for the same individual throughout the duration of the food restriction protocol. We show that our microscopic model of size dependent lipid release can predict macroscopic size distribution evolution.