hai,
I really appreciate your concern.
your understanding about
steroids and their effects also to be appreciated at this age.
I will advise you to gain weight in natural way.
Take protein nourished foods like Almond,cashew,channa,soyabean,peanut in your daily food intake.
Add jaggery,black gram,and dal prepared with ghee,fig,potato boiled and lots tuber type vegetables.
Take diary product like milk,yogurt,chesse,butter etc.
Take wheat, Millet and Multi grain Powder that with nourish you and stay healthy and gain weight.
As you want to weight eating the above mentioned food stuffs.
but junk foods, fried items also gain weight but it will harm your body.avoid junk,fried items and caffeinated drinks.
besides you have to do some exercise to strength your muscles.
be hydrated.
This will nourish in a healthy way and gain weight.
hope i answered your query.
Have a healthy Life. thank you.