Definition of obsess from The American Heritage Dictionary of The English Language New College Edition.

Obsess - To harass or beset like an evil spirit; haunt as a fixed idea, besiege
Obsession - The state of being beset or actuated by the devil or an evil spirit
Compulsive preoccupation with a fixed idea or unwanted feeling or emotion, often with symptoms of anxiety
A Compulsive, often unreasonable, idea or emotion causing such preoccupation

Has there ever been a better definition of food obsession?