feel 的确是动词,整个句子实际上是
I feel (that) you are much fatter than you used to be.
I feel 是 主句
(that) you are much fatter than you used to be 是从句
that 是连词, 被省略了
动词 are 接 you .
希望帮到了你,若满意请点击“选为满意答案”及时采纳,谢谢.