My cat is almost 6 years old and weighs 17 lbs.  She is chewing on things
and meowing to wake me up in the morning so that I feed her. Because of her
weight problem, I feed her two 1/4 cup servings of IAMS dry weight control
cat food.

She is an inside cat, so she's not that active, but she has a little sister
cat, who is now 3 years old and they chase each other around. Her little
sister cat is now also is looking overweight and weighs around 15.5 lbs.,
and I've been feeding them both the same food and the same amount of food
for over 3 years now, and no results. Just lack of sleep for me!

I tried giving them more food so I could sleep, but then they looked like
they gained even more weight.

I have taken them to vet and asked him for advice, so he gave me Hills
Prescription Diet r/d and I tried that for a few months and there really
wasn't a change, so I went back to the IAMS weight control. My vet said
there isn't anything really wrong unless they both gain alot of weight fast.

What am I doing wrong? What should I do?

Please Help. Natalie