Alternatively, all the characters in Alice's Flashbacks are literal stick figures which may or may not include Alice herself.
Alice, a petite 4'5'' girl, was once the size of a house.
Alice was a living skeleton all her life and somehow she managed to be fat in her youth.
Alice claims that she's lost weight, but old photos show that she was just as fat. More recent photos, however, show that she did lose weight for a while.
Alice was Hollywood Pudgy as a child, which drove her to anorexia as a teenager. After entering therapy and recovering, she became overweight deliberately in college order to prove to herself that being Hollywood Pudgy again wouldn't be the end of the world. This helped her to get over her weight issues, and now she maintains a healthy weight by healthy means.
Alice has maintained a healthy weight for her whole life.
Alternatively, Alice is still overweight.
Bob: Wow, Alice, you used to be fat. I mean, really really fat like a submarine. Charlie: Woe, woe, hey, you shouldn't say that! Since when were submarines fat?
Invoked: Alice's mom, Karen, tries to help Alice go on a diet.
Exploited: Claire uses the fact that Alice used to be fat to lower Alice's self-esteem.
Discussed: "Don't worry, Melissa. I bet that mean old bully used to be a fat chick when she was younger."
Conversed: "I bet the writers just made her past-self fat to garner sympathy points, either that or make a bunch of fat jokes. I don't know which."
Deconstructed: Alice lost all that weight owing to severe problems with self esteem. She's now at healthy weight, but honestly can't get herself to belief it.
Reconstructed: Alice eventually gets over her self esteem issues and learns to be happy with herself the way she is, feeling better socially and physically, as well as mentally thanks to the help.