feeding a cat that has been neglected

How do I reassure a neglected cat that I will not let him starve?
   
We have taken in two new cats; a male adult, and a female kitten. They were removed from their owner because of neglect; the floors of her home were covered in a layer of animal waste. No cat or dog food was found in her house, and the water had been shut off by the water dept and there was no fresh water for the two cats and two dogs that were in the home. I saw a photo of the male cat from about a year ago and he looked a healthy weight. He is now very skinny compaired to the photo, but not underweight (he weighs about 11.5 lbs). Since we have taken him in we have noticed that he has major issues with food. We feed our cats on a schedule (one of the cats we already have has a habit of over eating) and we feed all our cats Innova Evo's Cat and Kitten formula. But he is constantly hungry and scavanges for food. We cant leave any food out (even loaves of bread in the plastic or packages of hot dog buns and the like), and I have a feeling that he is drinking the water from the dishes we have soaking in the sink over night. He is eating toys and other objects that are not food; he even tried eating a raw potato. The vet gave him a clean bill of health. But I dont know what to do with his hunger issues, we feed him snacks but he still jumps on top of the fridge, opens cabinets, etc to get to more food resulting in horrible diahrrea. When he eats at meal time it seems like he is afraid its going to be his last meal. What can I do to reassure him that we are not going to starve him like his previous owner?

He's overcompensating. He will likely outgrow it when he realizes that he's not being starved. (I had a cat I got off the street that did the same thing. Once he stole a whole steak from my plate.)
   
You'll have to lock everything away in the cupboard until he calms down & gets rational.
   
And you might want to call the vet & ask if there's an appetite suppresent for cats out there.
   
Also search the holistic pet sites for anything that may help.