Mostly it comes from our diet and what we eat. We've become accustomed to eat for our senses (taste) instead of our survival (nutrition). We're addicted to th

Mostly it comes from our diet and what we eat. We've become accustomed to eat for our senses (taste) instead of our survival (nutrition). We're addicted to the taste of 'good' food. Then you have food companies who are engineering that addictive taste for your senses. A habit develops and it's hard to shake that off.