Shes not fat...!:((((?

my mom is always saying that shes fat and it really upsets me. Im always trying to tell her that shes not fat but all she says is "ooooh yes i am!" but she says it more in a playing around way. and shes even thinking about getting lipo suction!i really dont want her to :( it just makes me sad even thinking about it! does anybody have any ideas of what i can say to her to make her realize shes not fat? by the way im only 13 :(