How to deindent text within itemize

Question

I have an itemized list that looks like this:

  1. List item
  2. List item
  3. List item
  4. List item

How do I insert deindented text (specifically, a proof) so that the output looks like this?

  1. List item
  2. List item

PROOF HERE, deindented, generated with `\begin{proof}` command

  3. List item 
  4. List item

Answer 1

Instead of inserting the proof in the list and adapting the indentation, you could just resume the enumeration after using enumitem's resume keyword.

\documentclass{article}
\usepackage{amsmath, amsthm}
\usepackage{enumitem}
\begin{document}
\begin{enumerate}
    \item List item
    \item List item
\end{enumerate}
\begin{proof}
The proof.
\end{proof}
\begin{enumerate}[resume]
    \item List item
    \item List item
\end{enumerate}
\end{document}

Answer 2

Without using enumitem:

\documentclass{article}
\usepackage{amsmath, amsthm}
\begin{document}
\begin{enumerate}
    \item List item
    \item List item
    \label{lastitem}
\end{enumerate}
\begin{proof}
The proof.
\end{proof}
\begin{enumerate}
    \setcounter{enumi}{\ref{lastitem}}
    \item List item
    \item List item
\end{enumerate}
\end{document}