Polysaccharide extract (I) derived from a mushroom of Lentinusgenus for treating cellulite and subcutaneous fat deposits, is claimed. ACTIVITY : None given. MECHANISM OF ACTION : Sirt 1 activator. The ability of (I) to activate Sirt 1 was tested in HaCaT human keratinocytes. The result showed that the extract of Lentinusexhibited an increase of 500% of the amount of Sirt 1 present in keratinocytes.