I disagree. Fatphobia is not a made up term. Fatphobia exists, and I've suffered from it. And I still do. Regardless of the skin color, fatphobia is a thing and saying it doesn't exist just diminish fat people experiences and invalidates them.

While that doesn't inherently mean that you're fatphobic, you're not entitled to anyone's body and you shouldn't be commenting on their bodies, and it doesn't matter if you have good intentions or not because the other person is the one who will feel bad about it.

A definition from Macmillan and Dictionary that says: "irrational fear of, aversion to, or discrimination against obesity or people with obesity". It's not about fear, it's about discriminating. And that happens a lot.