Hello dear, You are correct regarding the fact that eating chalk is harmful. Chalk as well as slate pencils contains calcium carbonate which if taken in excessive amount can cause stone formation in kidneys. The continuous craving for eating inedible substances (like chalk, slate pencils) is known as Pica. It is one of the features of Iron deficiency anemia. Investigations like complete blood count & peripheral blood smear will be helpful in clinching the diagnosis. Based on the reports, management will include administration of supplemental Iron & Folic acid preparations. There can be associated factors like hookworm infection which needs to be managed with Albendazole preparations. Also you need to take a healthy balanced diet rich in green leafy vegetables. Your weight will also improve with all these measures. So, kindly consult your General Physician for proper clinical evaluation. Wishing you a good health. Take care.