Thank you for posting your question.
Low appetite is a common and overrated problem in children. First of all what needs to be known is whether actually your child does not eat well or is it just that your child does not eat as much as you expect him to. To know this you need to study the weight and height patterns of your child. If he comes in the normal range for his weight and height for age and there has been no dip in the same, you could relax knowing that your child is eating as much as his body needs in order to remain active and healthy. If there has been a fall in his weight or height, then you probably need to do something about it.
You could introduce home made food for your child and make sure it suits his
palate. Trial and error would help you know what is it that your child likes to eat. Prabably a change in the consistency of the food may make it more comfortable for him to finish his meals.
Multivitamin supplements like
zincovit it may help as they might have mild appetite stimulating effect along with supplementation of deficient
vitamins.
Deworming may be done every 6 monthly and a single night time dose of drugs like ablendazole may be used. If nothing works, then there are appetite stimulating drugs which are under trial but I suggest you keep that as the last option as they are not commonly prescribed in children and are better avoided.
Along with the above mentioned methods, patience and regular monitoring of weight and height would definitely help you to deal with this.
Wishing you all the best, if you have any more doubts do write back.