Model of lipid metabolism is developed in the framework of Etherpaths project (FP7) - Characterization and modelling of dietary effects mediated by gut microbiota on lipid metabolism, which is focused on the systems biology of lipid nutrition. Our aim is to develop a metamodel of digestive, lymphatic and blood circulatory systems of human being which describes effects of nutrion on lipids metabolism in various tissues. It becomes possible only with help of such tool as CIRCULATOR software, because simulation of the digestive, lymphatic and blood circulatory systems requires for plausible predictions methods of systemic modeling. It is also important to validate this model for integration with different types of experimental data and modelling results obtained in ETHERPATHS.

Metamodel takes into account the following processes (see the scheme on figure below):

1. intestine:

• fatty acids uptake from dietary fat,
• chylomicrons formation;

• fatty acids and lipoprotein particle transport across the organism;

• chylomicrons and VLDLs binding and hydrolysis and remnants formation,
• release of albumin-bound FFA to blood,
• FFA utilization (muscle) or storage (adipose);

4. liver:

• Albumin-bound FFA uptake,
• VLDL1 and VLDL2 formation,
• Remnants uptake and utilization.

Such detail description of the folowing processes allows developing a systemic model which simulates whole cycle of lipid metabolism. For example, from one side using methods of detail kinetic modeling allows taking into account biochemical structure and properties of lipid transformation which take place in a human. From the other side using of CIRCULATOR software leads to simulation of digestive, lymphatic and blood circulatory systems as flowing systems and taking into account physiological tissue functioning and specifity. All these facts make developing model a novel and high innovative approach for studing the nutrion problems and issues.