Interest in the follow-up of fatty acid composition(saturated, polyunsaturated and monounsaturated fatty acid) in the body is growing. Quantitative MR spectroscopy can give access to this fat composition. Today, several quantification methods are used (e.g LCModel, AMARES). However the statistical outcome issued from a quantitative analysis of the lipid signal can be greatly influenced by the used quantification method. We analyze 1) the impact of the time sample selection and design of the model function on the parameter identifiability 2) the quantification results obtained with different quantification models on acquisitions performed in vitro (oils) and in vivo (subcutaneous adipose tissue).