Our Fluffy is just a tiny little thing too! Just a bit over 7 pounds. She eats as much as the other 3 and in fact since she is so tiny we try to sneak her extra treats and let her free feed at the "crunchie machine" which is behind a closed door so that it isn't available to everyone all day, but whenever she wants in we let her. I think she just has one of those metabilisms that burns it off quickly (wish I did). When she jumps up on us at night in bed you hardly even feel her she is so light.