However, usually, the cause is excess intake
of milk and liquid (juices, soups, carbonated drinks etc). This gives them the required energy, and hence they do not take the pains of chewing and eating. Hence, first you will need to check if this is the cause, and then reduce this. Secondly, diverting their attention to stories, cartoons, miming etc while feeding often works. Third, you need to find out if he has any feeding difficulties. Fourth, you need to bring variations in food.