This probably falls under some "wholistic approach" myth towards dieting. This is a very tricky idea but it's one I hear a lot from various people in my life. I have NEVER once seen an article addressing this assumption about hunger and it might simply be an urban legend/hypothesis or folklore. People that I meet make this assumption all the time. There is no link or source or paper that I know of regarding this. It is urban folklore as far as I can tell. Can the human body cause a sensation of hunger for the exact nutrients it needs (to be healthy) at a specific time? A craving for protein, carbs, salts, fats and then into specific vitamins and proteins etc because that is the exact requirement at that specific moment? If a person is hungry and craves fish (seemingly at random to the person) is there any evidence that this person requires any nutrient that fish provides at that specific time? Another example. Oysters are high in zinc.. Is there any evidence that a person craving oysters is lacking in zinc? That is just an example. It would seem like a very tough phenom. to study. I am not talking about a general sense of craving food when you are simply hungry (I can understand that.) I mean hungry for a very specific food that has a very specific nutrient that you just so happen to be depleted in. Many people I speak to assume this to be true but I am not so certain it is true. I get ice cream cravings, chocolate cravings but mostly cravings for salty food : none of it is a healthy craving. Although occasionally (rarely) I will desire a food like broccoli and mention it to my wife and she will say "You probably need iron."