Mommy cat going nuts..

My kittens are almost 4 weeks on friday, and the mommy cat is going nuts.
Every time I try and feed the kittens weither it be soft cat food or kitten food she tries to take over and eat it all before they can. Her hair stands up on end when she is doing this. She is acting like she is starving, but she has an unlimited amount of cat food to her eating (and she is very much eating a lot of it) and I even give her about a 3/4 to 1 cup of kitten chow for herself every day. The kitten food gives her diahrea thats why im watching how much I am giving her. Last night she also jumped up and grabbed chicken off my plate and her hair went up again. I don't understand this. She is still the loving cat, but she is now meowing a lot more and I had to hide the cat food and even the regular bag of food (that she has in her bowl and lots of it all the time) because she is tearing the bag up trying to get inside. Please if anyone knows what to do please tell me.

Thanks!!

She will need a lot of extra calories while she is nursing. If her tummy is getting upset when she eats certain food then shes even losing more nutrients. Make sure she is on a premium high calorie food and give her plenty of wet food, its really important for her and her nursing babies.