Common response and completely misses the point. Its about dosage.

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.