I don't like this song that much, mainly because of the lyrics.
Of course I understand that it is supposed to be funny and over the top and that's smart, but I can't help it I just don't like the lyrics
The song is of sort of poking fun while being in the joke at the eccentricities and excesses of being rich, beautiful and famous (Dress in silk, use black cards, ask friends for advice before having a tan in Taipei, looking what's hot) hence the heavy references to the fashion world in the lyrics and the title, 'Donatella'.
That line references the lengths and extents that someone has to go through to be thin. It's because of the mention of the runway in the previous line of the verse, of course, that she's talking about a model or someone aiming for beauty. Remember Gaga, as a pop star had to go through to the same standards as fashion models so the analogy with her life is understandable. She might be talking to herself or a second person who's already eaten a salad in the day, in a way of a mantra (it's common for people who have goals to use mantras): "Boulangerie!", which is french for bread shop so that would most likely suggest she, the person or model is going through an all-carb diet.
The use of french might also suggest that she's most definitely referring to the fashion world, 'cause french, because of Paris, is closely tied to fashion. She, again, might be talking of the hardships she had to go through to stay in shape to be a pop star using the fashion analogy. So it's easy to conclude that she's making fun of all she had to go through to be the model people look up in a superstar. The humor and jokes it's part of the pop part of the album and the struggle is part of the art part of it.
It's meant to be fun/funny but with a little bit of a dark humor/satire because not all the things she's referencing in the song are like that in real life.
I don't disagree with anything you said. But it's still **** writing. Like embarrassingly bad.
Songs like Donatella make ARTPOP's metacritic score of 61 look generous.