do you mean to say low levels of caloric restriction, or low levels of caloric intake?
Water will quench your thirst. You can also drown in it.
Fire will warm your hands. Sticking you hands in a fire is a bad idea.
Acute stress, induced by exercise / caloric restriction, is feedback to trigger beneficial cellular behavior.
Chronic stress, no exercise / eating poorly through starvation or overconsumption (a “heroic dose”) will certainly kill you sooner.