I once read a book (don't recall the title) that spoke about listening to your body's cravings because usually it indicates that something is missing in your diet that your system needs. It spoke about how infants/ toddlers go through stages and sometimes will eat a lot of certain foods, but then will go through periods of rejecting favorite foods, and this book claimed that even at that young of an age the infant's body is eating what it needs.
I read the book when I was very young and I don't recall it being based upon any scientific research (although it may have)....... but in my own life I have found this to be true to some small extent. For example, once my morning sickness from this past pregnancy had subsided, I found myself suddenly craving hamburgers. I couldn't get enough of them. I was eating them for lunch and dinner. Ironically, when I had a blood test at the doctor my iron levels were low-- just below the normal range. I have never had low iron in all my life and at the time I was also taking a prenatal vitamin with iron in it, but for some odd reason I had low a low iron level -- and as you know, beef contains iron (although a hamburger is certainly not the best source of iron

). Anyhow, that is just one example.
Sometimes my body craves water and I will drink it to no end. If I eat a greasy, dense protein then suddenly I find myself needing something sugary. (My mom is the same way.) Too much sugar and suddenly I crave salt. Every now and then I get a craving for those spicy pork rinds.
I better stop listing my cravings...... I've already been called a fatty by one member of this forum.