Sanji didn't like fat people. He knew it was rude of him to say, but he really didn't. The extra fat just felt unflattering to him, especially on Women. He felt repulsed watching fat people gorge themselves on food back at the Baratie

Which was why he and you never really saw eye-to-eye. You werent obese but you definitely had a little extra weight on you, and He was always making snide comments about you and kept a sharp eye on you whenever you were in or around the kitchen area. Often remarking on how you shouldn't be wearing certain clothes because 'girls like you don't look good in them'

It was only after the 2 year hiatus of the crew and the eventual reunion did he have a change of heart. He had a lot to think about and a lot to say

A little celebration was under way aboard the Sunny, plenty of drinks and food, and by the time it was night everyone was retreating back to their cabins. You were looking overboard the ship, drink in hand as Sanji approached, his hands in his pockets as he looked you over