I think the worst part is being hungry. I think the worst part is hungry. 兩句差個being，文法上差在那？being作何解？

The worst part is [being hungry].
The worst part is [hungry].

在上列两句子中, [...]都是主詞的補語, "hungry"是形容詞(作用是describing the subject), 而"being hungry"則是屬名詞性質的動名詞片語(作用是renaming the subject).

第一句語義關係上是同位語, 位置基本可以互換:
Being hungry is the worst part.

第二句在語義上好像解不通, 錯誤地將非人性的主詞(impersonal subject)與人性感覺的形容詞連綴在一起.

動名詞 "being" + adjective 代表著一種狀况(condition) 或經驗(experience).

From your recommended bk by TW Chen's the heart of grammar, which part of past participle and present participle ---_which you've asked too much_----, are you not in usage understood?
being hungry=n phr=A/subj=co-or=A=B
ie:-A=being hungry=worst part=B
When the Chinese treats it as a verbal, gerund=being+adj=conditional, experienced
ie:-Not Kuangkwo thinks the worst part is hungry ; but   Kuangkwo thinks the worst part is being hungry.
but, verbal phrase tells what Kuangkwo does, experiences on connected words and their usage on " Participle."
Yet;
"participle"=being + adj=qualifying a condition, emphasizing the fact=a compound v=adj
ie:-"Being" hungry, Kuangkwo needs participle-----------qualifying and emphasizing(the fact on a "Participle")

希望你能分辨中文「狀況」跟「情況」的分別：

Being hungry是表達「狀況」= 長期/維持 或用點想像ing是"進行的"。若要翻譯：饑餓 或 餓著
hungry是表達「情況」= 一種感覺/現象。若翻譯：肚餓 / 沒法得到需要吃的。

很難怪華語人對這種英語人用being作為修飾或突顯作用有時會誤會。

從文句意義上說，以上兩句的worst part雖然同樣字詞但代表兩種不同對"沒食物"的不同感受。

being 是被動式，你被強制捱肚餓，是人為的，例如被關上集中營，你知道什麼是集中營嗎？沒有being是天意，例如大饑荒