Advice Needed

My L.O is a year and 10 months. And I have a problem getting him to eat. I'm lucky if he eats once a day. I have always had a poor appetite, so I'm not sure if it's genetic or not. But I'm really starting to worry because he lost some weight but the doctor told me his weight is fine for his age he weighs 11kgs now after weighing 15 kgs at his 18 month check up.