First, have you tried the Zoom Groom brush for cats? I know many people who swear that the Zoom Groom picks up more hair than any other brush. I haven't tried it myself but here's a link:

Zoom Groom

There are also these treats that are also supposed to help:

Hairball Prevention

I really can't say that IAMS is better than Science Diet, or the other way around. Actually, I try to stay away from both of them! If Nakita needed a food for hairball control, I would go with the Flint River Hairball Management Formula. Click on the link and scroll halfway down the page to find the description:

Flint River


You may also try a higher fibre diet for you cat. This will help with any blockages that may occur because of the fur. Try adding a half a tablespoon of canned pumpkin to some wet food.

Also, many cats will lose more weight on canned food rather than dry food. So you might want to feed your cat more wet food and you will have the added benefit of getting more water into your cat! It also couldn't hurt to talk to your vet about your concerns. He/she may be a couple of other suggestions.

Good luck!