Weight loss and Chicken Soup for the Cat Lover's Soul Cat food.....

Hi,

My tomcat (~5 years old) has been eating Hills Science diet for the
past four years and he has really loved the stuff. Recently I was
chatting with the person at the pet store who claimed that science diet
is inferior food and she recommended Chicken Soup for the Cat Lover's
Soul. She ended up giving me a bag for free. When I ran out of science
diet I started feeding the cat the Chicken Soup stuff. He seemed to
hate it but nonetheless I continued feeding it to him and he seems to
have warmed up to it -- he still is not impressed. He was a fairly big
cat, 18 lbs not fat but pretty chubby before the switch and has lost
3lbs since then (about 5 weeks ago). I am not sure if that is due to
the fact that he doesn't like the food or that it is better quality.
Other than the apparent dislike for the taste of the stuff he seems
healthy (shinny fur, clean, alert) and if anything he is a lot more
active.

The two questions I have a

1. Is the Chicken Soup really superior to science diet?

2. Do you think that his weight loss will eventually stop and he will
hit some target weight? If he continues to loose weight do I need to
switch him back to science diet?

Thanks,

Matt