A craving for onions is an indication that the liver is not functioning as well as it should. These cravings mean the body is lacking sulfur. Onions contain sulfur, which improves liver function.
It is important for the liver to function properly because the liver helps to break down toxins and balance hormones. Eating a lot of greasy foods can be the source of decreased liver function. This strains the liver and does not allow it break down food properly. There are a few physical signs that mean the liver is in distress, including yellowing in the eyes and the nails and red spots around the eyebrows.