The most basic drive we have as human beings is the drive to eat. We eat primarily for survival. We eat secondarily for a variety of other reasons.

But when the physical can successfully be denied in the pursuit of the spiritual, discernment and victory increase dramatically (when done scripurally).

Why?

I can't give all of the reasons, because I don't know them. But I do know that the downfall of many who struggle with addiction is the problem of instant gratification.

Fasting is a big help in this area. In addition to practicing patience, self control and self denial - spiritual assistance  against spiritual wickedness is available, as a result of fasting, that can be obtained no other way.

There are some demonic strongholds that cannot be gotten rid of except by prayer and fasting - Matthew 17:21 (if your Bible leaves this critical piece of information out (many do) or has wicked subjective footnotes (the devil loves these) that say the "oldest and best" manuscripts don't include this verse-- discard that butter knife and get yourself a sword (King James Bible).