Why are we arguing about the yeast in the pills Barbieri took? Was it even as much as a gram? According to the writeup I read, the pills were vitamin pills, and the yeast was only a small part of the ingredients.
So 0.4 g of protein a day, tops? How is that even relevant here, on either side of the discussion? That small an amount is not likely to have had an effect on autophagy, nor does it provide enough calories to break a fast.
All I know is that, whatever Angus Barbieri and his doctors did worked well, because a comparison of before and after photos is stunning.