What the Bible says about Spiritual Vitality
(From Forerunner Commentary)
Though God commands us not to eat certain animals, fish, and birds (Leviticus 11; Deuteronomy 14), the person who lives by sight rationalizes that these are merely ceremonial laws. At least part of the reason for God's command, however, seems to be that the bad effects of eating unclean meats are not immediately apparent. Problems resulting from a steady diet of forbidden flesh may not show up for 40 or 50 years or even until the next generation. If one chooses to ignore God's gracious command and persists in eating things He has not designed as food, sin eats away at his physical and spiritual vitality.
John W. Ritenbaugh
What Sin Is