Food is addictive because all animals including humans are by our very genes instructed to be addicted to it. Even the most healthy food is addictive. Just like water and air is addictive.
No you can’t say that. Fat people don’t get fat on eating vegetables and water.
I don't think "addictive" is the right term, but we have an evolutionary imperative towards eating to excess when there is food in excess, which wasn't maladaptive until recently.