Fish react to .... too much of a good thing similar to the way humans do.
When we constantly eat too much, and become sedentary, we clog our arteries with lipids and abbreviate our life span, and health.
If we imbibe too much, we get liver disease.
We love the process, but not the end result, just as fish will constantly gorge without reservation.
When we feed our fish too much, and especially too much protein without providing something to clean out the gut, and without enough space provided for adequate exercise, our fish can get fatty liver disease, which sometimes manifests as bloat, HLLE, and infected swim bladder.