The weight liver is one of the important selection criteria in the quality of foie gras. This factor is highly variable despite the fact that individuals are reared, force-fed and slaughtered in the same way. In this study, an analysis of the proteome profile of two weight classes of light (between 550 g and 599 g) and heavy (more than 700 g) livers. For the analysis of the proteic extracts, a liquid chromatographic analysis coupled with mass spectrometry was carried out. In livers with low weight, aerobic energy metabolism, protein anabolism and lipid metabolism oriented towards export and beta-oxidation was overexpressed. However, high weight livers was characterized by anaerobic energy metabolism, more active protein catabolism associated with cell death by apoptosis and reorganisation of the cell structure.