Stress relates to nutrition in that ... and it relates to substance abuse in that ... please help

stress relates to nutrition in that the more stressed a person is, the more likely he'll crave for food or not eat at all

and it relates to substance abuse in that stressed individuals sometimes make poor choices in managing stress

Explanation:

"Stress" is a normal reaction of a person's body when faced with unexpected, challenging or demanding things.

The more stressed a person is, the more likely he'll choose unhealthy foods or those foods which are high in sugar. At this time, it is the person's comfort food. There's also a possibility that the person will not eat anything at all or skip his meals because of overthinking or doing many things.

Sometimes, a person makes poor choices in managing/coping with stress such as turning into substance abuse, smoking, binge-drinking and so on.  

cheetos? that's the answer? ?