What you’re talking about is Autophagy - the link explains more but it’s an intelligently regulating system.
It specifically targets dead, dying, and damaged cells first (senescent cells), supposedly at the DNA level. The same process increases new cell creation (shown in immune cell studies).
“A 2020 review article explored the ways autophagy may help protect liver cells from drug- and alcohol-induced liver injury”… well duh, hard to get injured from drugs or alcohol if you are fasting. /s