Room service does include hot food items, but you are welcome to bring food back to your room.
On one of our cruises my Dear Wife felt a little ill (tropical depression) and left the dinner table. She left the table and our server brought me our meals "to go".
A Bad Day At Sea [with power] Always Beats A Good Day At Work
Carnival: Glory 2004, Destiny 2008, Splendor 2009, Freedom 2011, Valor 2012, Dream 2013
Celebrity: Summit 2011
Princess: Ruby 2010, 2014, Caribbean 2013, Coral 2014