Question: how to gain weight quickly after illness?
Answer: Milk. Share on Pinterest Protein shakes can help people gain weight easily and are most effective if drunk shortly after a workout. ... 
Protein shakes. Protein shakes can help a person to gain weight easily and efficiently. ... 
Rice. ... 
Red meat. ... 
Nuts and nut butter. ... 
Whole-grain breads. ... 
Other starches. ... 
Protein supplements.