1. Reasons for a baby’s poor appetite There are many reasons for a baby’s poor appetite, which may be physical discomfort, environmental changes, improper food selection, etc. Among them, the most common reason is that digestion is not fully developed and problems such as diarrhea and constipation are prone to occur. In addition, if the baby is too picky about food, it can also lead to malnutrition. 2. How to judge your baby’s appetite