Yes, it's fat shaming, because a celebrity's job is generally to act, or sing, or play an instrument or present a programme or play a sport. Outside of that very limited scope, whatever they are/do/eat/read/buy/wear/whatever is no-one else's business and they shouldn't be up on some kind of pedestal for it. As long as what they do is legal and doesn't hurt anyone, it shouldn't be something you care about.
Yes it's fat shaming, because so many people are fat nowadays that it's more of a cultural and societal issue as the root cause than just their individual laziness. Change society and culture, you change the individuals.
Yes, it's fat shaming, but so what? Should they be ashamed? If so, then fine... but given how many of the world's problems come from overpopulation, is it not good that we'll be rid of these fat people sooner?
All in how you wanna look at it....