Do guys feel inferior because they are skinny?

I was talking to my crush the other day. We were discussing the physical build of our friends. All of a sudden, he got kinda insecure. He started saying that he can’t gain weight no matter how much he eats. He says he is too skinny. (FYI: his BMI is <17) I was taken aback because he seems to be confident most of the time and I didn’t know that he has his security issues. So I went like I think you are not too skinny. You look normal to me. (to be honest I like him so much I don’t really care what his BMI is but of course I didn’t say that).
He didn’t seem very convinced.

Is this a common issue for guys?
Do guys feel inferior because they are skinny?
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