We are currently overtaxing natural resources, human population cannot grow unbounded without many unpleasant consequences. To me, it’s not a problem if we reach a steady state or even start a slow downward trend.
But, we must turn away from “line goes up” methods for measuring success, which are pretty deeply ingrained in most of our economies.
What about relative energy (energy per mass) - if poop is less energy dense than the protein/fat of your tissues, excreting it should increase your energy density