Hi,
Protein preparations and protein rich food is always advised in lean people. You can consume the following vegetarian food which are rich in protein - milk and milk products like curds, butter, panneer, cream, cheese, ghee, etc.; sprouted wholegrams like channa, bengaal gram, greengram, rajma,etc.; nuts like almonda, walnuts, pista, groundnuts, etc.; pulses like toor dhal, black gram dhal, bengal gram dhal, greengram dhal, etc. Non-vegetarians can take egg, meat, chicken, pork, fish, mutton,etc. which are also very rich in proteins.