It comes down to the way it was said.

Good = "honey, you've been making comments that you're unhappy with your weight. I would like to help you lose it so you can be happier."

Bad = "wow, you're looking fat lately. You really have to lose some weight."

As for being called fat: I've been fat my entire life and couldn't lose weight until last September. One of the things that helped me start was looking myself in the mirror and saying, "Ok, I'm fat. I've neglected this facet of my life. It's not attractive or healthy. Own it, it doesn't mean you're a bad person."

Granted my situation was a lot different from yours. I weighed 342lbs when I started (down 93lbs so far), which is a lot different than wanting to lose 20 pounds. "Fat" is a word that is subjective. Don't let it be used as a weapon against you because it's just a word.