Hi Sir. ORSL has more sugar than standard ORS. So it may make him overweight over long-term.. Also sugary drinks can cause tooth decay. Better to  for natural drinks like buttermilk, tender coconut water, fresh fruit juices(homemade, not commercial) without added sugar or normal ORS like Electral etc. He can as well eat whole fruit(best option) like water melon(best for hot summers) , eat banana or apple and drink lots of plain  water.