Very nice picture. It's a great version of human Celestia, and the before-and-after picture shows the contrast between her growth quite well. The way her outfit changes to fit her is very cool as well, like how she now shows a lot of cleavage and how it's a lot tighter on her midsection.
The Celestia on the left was taken in the B.C.-era I'm guessing. ...B.C. standing for "Before Cake." Bad joke, I know, I couldn't resist.
Nice work on both thin Celestia, and chubby Celestia, they both look cute, and pretty, and I like the differences between them. You did good job humanizing her a bit to. Their wings are a bit tiny, but they look good still.