He can have 3 gms of salt per day. Generally all fruits and vegetables are allowed. Avoid saturated fat such as butter, ghee, coconut oil etc. Should it be refrigerated or can it be kept outside. I soak 4-5 almonds everyday at night in water and remove the skin in the morning and eat it.
Almonds are high in protein, fat, calories, vitamins, and minerals.
Yes, it will help you to put on weight.