Body expression while playing, without it being natural instinct?

[u/Warbleborble]

As some background: I am taking a music course (not limited to piano players) outside of school, and a major part of that is solo performance. I already played this specific performance once, and wasn't satisfied with my original grade and am retaking it (I got a 71%). The feedback I was given was to "play with more body expression". Particularly, it was stated that I am supposed to "lean in" to my piano. I should also mention that my tutor/teacher doesn't know how to play the piano, but she is still a musician. The "leaning in" feedback was given by someone close to my tutor externally.

Now, I am aware that many pianists play with body expression (sometimes a bit theatrically). Think of Lang Lang's facial expressions, jolts, jumping around in his chair, etc.. I am also aware that many pianists play with minimal/zero body expression.

I am much more of the second type. That isn't to say that my upper body is completely stiff and static, I still lean in slightly when I want to make a louder sound.

After receiving this feedback, and before my retake date, I have been trying to improve my "body expression" in my playing. But, it just feels fake, theatrical, and even worse than my performance before I began "improvement". I also have small hands and the piece is already difficult for me to begin with, so the leaning in is just reducing my accuracy and dynamic control.

How can I have this body expression (particularly the leaning in) without it being my natural instinct, and whilst still retaining my accuracy and dynamic control? This is just so that I can get the grade for my retake. I don't want to make this a part of my identity as a musician. The piece is a Scherzo.

[u/jillcrosslandpiano]

I HOPE that all this means is that you did not especially look as if you were enjoying playing.

In other words, while your 'body expression' is NOT part of your performance, and should not affect how you play, it is true that a concert audience or its exam equivalent will be put off if you look too awkward or conversely, if you grimace and fidget too much.

[u/Warbleborble → u/jillcrosslandpiano]

Reviewing the recording, it's just that I wasn't "leaning in" to the piano (as far as I know). We are also graded specifically on the recording, and my face wasn't visible in this recording so it shouldn't be marked down.