To add to this, I’m not sure about fitness models exactly, but I know in the modeling industry for commercial and clothing etc pretty much every model is already at their desired weight and muscle tone and then maintain that long term.
At any time the agency can call and ask for photos of you and if you’re not presentable, say good bye to that client and money.
I can’t think of anyone, including myself, who goes on a bulk and doesn’t look somewhat bloated.
As for Instagram in general, photoshop and selective photo taking. That simple. Don’t take photos when you look like shit or, use photoshop to make yourself look good if you do. Just don’t buy into the bs, so much of the modeling world is fake, specially when you’re apart of it and can see it from the inside.