she feels fat and IDK what to say??

One of my best friends has recently started saying that she feels fat. She keeps saying it over and over again so I know it’s bothering her. She may have put on some weight but honestly she seems happy and healthy so who cares?  We are in our 30s and we’ve known each other for over a decade - we’ve seen each other through many stages of life and are open with each other.

I just know that it’s really bothering her and I want to say the right thing… I keep telling her she’s beautiful at every size but I don’t know if that makes her feel better or worse lol. What would you say or what would you want to hear??