Why should she be ashamed, or proud, of her "skinniness"? Why should she "hide" it? It's her body. People with curves are not ashamed of showing them. Skinny people should not be either. She' not ill. Had she been ill from 10 years now, she would be entered and not able to do a normal life (not mention to the fact that she had two children). Why on earth should she hide her arms just because they are not perfect?
The "skinny shame" this society is reaching ridiculous heights. Don't be skinny, but don't be fat either. Have some curves, but only if they're on your breasts and your hips, if they're on your legs that's obesity. For heaven's shake, let people have the body they have got, nobody in the world is perfect as a classic Helenistic sculpture. For today standards, seems like poor Audrey Hepburn should be covered up like a nun so she doesn't "set a wrong example". It's almost crazy.