Have a fracture (100%), got bit by snake, then ate so the shadow yellow bar was completely full, but the actual yellow bar was not actually full. This halted my food regen on all biles, even when I took the Ratler Serum, my food regen still didn't kick in, in other words I still had a shadow bar for several minutes. Eating serveral different foods still didn't make regen kick in, just making the shadow bar get bigger, but actual biles stay the same.
Normal tasks lower actual biles, but don't start regen. Wasn't until about 10 minutes, and/or picking up a boulder, did my regen kick in.