In article ,
"Jim Macklin" wrote:

I tend to say, "You look thinner in any dress." which is
totally wrong!

I usually don't respond at all which serves two purposes.
1) I have avoided having to answer the question.
2) I have deflected the ensuing response from the initial question onto
one I can successfully answer.

Of course, for those with hearing aids, you can pretend you didn't hear
the question and simply walk out of the room unscathed.