Hello!
No medication is required. Take him to a dietician and calculate his BMI and try to put him at 25. Also calculate his BMR.
Then come to planning of diet chart. He would require 2400 to 2800 calories as he is an adult male, active and exercising.
Divide it into multiple 4/5 meals per day.
Give him proteins as in eggs, milk, meat, soya, lentils which contain the highest dietary protein. Balance it with carbohydrates, some amount of fat, vitamins and minerals with sufficient water.
Take care!