Why did he say I’m not fat when I am?

We’ve been talking for a while. I was falling down on myself and he said he couldn’t understand why, that I’m very curvy. I’m not, though, I’m fat, and I told him that. He said “you are not fat at all, you’re thick and you look really good.” But it isn’t true. Why would lie to me
Why did he say I’m not fat when I am?
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