Eats one food faster than another?

Ok, so my kitty recently got weighed at 11 pounds and the vet said she needs to be around 8-9. She has been eating a small portion of wet food first thing in the morning, and about 1/3 c of Blue Buffalo dry food during the day. Usually she finishes the BB late at night or sometimes she will have a few pieces left over in the morning.

So, I decided to try to put her on Nutro Weight Management dry food to see if that would help her bring her weight down since she loves the Nutro wet food. I gave her a few pieces in my hand to see if she would eat it at all, and she ate all the pieces then tried to nibble on my hand because it smelled like the food. I thought ok great, she likes it! So the next morning I mixed about half BB half Nutro and she ate ALL the Nutro pieces in one sitting and left the BB behind. She eventually ate the rest though throughout the day. I wanted to see what would happen if I gave her all Nutro, and she literally ate the entire days portion in about two hours time! When usually she nibbled on BB throughout the day and it lasted her.

When she ate just the Nutro that day, she got really brave all of the sudden trying to get onto the counters in the kitchen, when we ate she tries to eat our food, and even tried to chew through a treat package! When she was on BB she never did anything like that, could it be she just LOVES the new food so much it's just making her crazy, or it's just not filling her up like BB does? This morning I put her back on BB just so I knew she wouldn't starve the whole day I'm at work. I've never had her act like this before for either wet/dry food and it's just boggling my mind. Has anyone else's cat done this before with a certain food?

From the way you are describing it, it would appear she really LOVES it...much more than the BB.  I might be inclined to think she wasn't satisfied with it IF this ere day two or three of her only eating the Nutro kibble,but that's not the case.  I can't imagine after just eating a few bites in your hand she would act this way if it wasn't a food addiction for this new taste .

BTW, many, many, many of us have found the best way to get our pudgy cats to lose weight is to put them on an ALL wet diet...no kibble at all.  It's really much more satisfying for them, especially if that wet food is high protein, low carb.  And three meals per day is plenty for a cat.  One in the morning, one when you get home from work, and one before bedtime.