I have a lot of experience going up and down in weight, and that happens to me almost every time. While I am gaining weight, my mind is behind the time and I feel like I am thin (and see thin in the mirror). When I am losing weight, I am much more aware of my lumps and bumps and see myself at a higher weight. It's pretty crazy.
It's a problem in both directions. It makes it harder to avoid gaining weight during maintenance and harder to feel happy with my accomplishments and know when to stop when losing weight. When I was thin for a long time, my mind did have a chance to catch up with my shape, but I'm not usually at the same weight for long enough.
Hoping to earn the user name NoYoyoMa...