Converting existing LVM volume to LVM-thin

Is there a way to convert an existing LVM volume (mounted as dir) to a LVM-thin pool without loosing the data? Where can I findnd more on this?

I can stop all VM's and LXC's - just would like to save some time on copying its disk files.

I have found this::
https://pve.proxmox.com/wiki/Storage:_LVM_Thin
But it doesn't say anything about loosing data (or not).