u've got 18.5 as ur BMI which is good actually. Normal is 18.5 to 22.5. So lets come to the point.
1. A normal person needs 1g/kg of body weight of proteins
. And as u might be already knowing muscles is all proteins. Body builders require actually 1.5-2gms of proteins/kg. and you know that u get proteins from eggs and non-veg sources like lean meat and if u are a non-veg. eater then u should atleast consume 3-4 eggs in the morning(Plz take note that u shud eat only the white of the boiled egg and not the yellow stuff as it contains all the cholesterol
which trust me u don't require).
2. Divide ur meals; instead of a standard 3; come to 7. Don't be shocked as studies have proven that less amount of food eaten at small intervals aids
digestion process in the body and increases the metabolic rate which is awesome.
3. As i said before, take plenty of chicken meat in the meals. Eat less in a meal and completely avoid fats in your diet like ghee, butter, lassi, eats.
4. Take plenty of fluids after an exercise session. It will really help ur body if u can add some salt and sugar in your energy drink. Nimbu paani is ur best choice but it should be homemade as the one's available in the market really suck.
5.Last but not the least, from my own experience, do take some proteins supplements like Soy powder available in the market. DO NOT GO AFTER WHEY PROTEINS OR STEROID
INJECTIONS AS THEY CAUSE MORE HARM THAN ANY BENEFIT TO THE BODY.
Happy Body building.