The present invention provides a kind of medicament, prevent from increasing total weight (or for reducing human body weight) or antiobesity agent respectively include at least one group be selected from consisting of the following group: EPA and pharmaceutically acceptable salt, ester and its derivative as active constituent, it is wherein used for the fat increase liver lipid formed or mild fatty liver occurs, the generation of the increase liver lipid being preferably formed as or fatty liver is not observed.
