Let $f$ be a measurable function on a finite measure space. If $f \notin L^p$ for all $p > 1$, is it true that $f \notin L^1$?
Unfortunately the inequality I am using to prove that $f \notin L^p$ does not work for $p = 1$, but I'm hoping for some kind of "continuity of the norm" argument whereby $\lVert f \rVert_1 = \lim_{p \to 1} \lVert f \rVert_p$ would imply that $\lVert f \rVert_1 = \infty$, but obviously the limit argument is not defined.