What I found was that when my Bengal was young, he was fat. As he got older, he leaned out, to the point that he is now quite thin (especially in comparison to my Egyptian Mau).
What I found was that the high protein dry food (like Applaws and Orijen) allows my 2 to put on more weight. I guess this has something to do with cats only being able to digest/process protein.
As my Bengal has grown older (he is 4 years of age now), he is now extremely fussy about what he eats. He will first smell it. Then rub his nose in it. Then if he likes it, he will eat it. Some times when I force something down his throat like a worming tablet or paste, he will actually spit it out. He is extremely fussy.
I bought some raw food from here:
http://www.naturalinstinct.com/categories/Cat-Food
...it is very high quality food and probably good enough for a human to eat
My bengal doesnt touch it. He smelt it quite a few times and one licked some blood...but didnt take any interest in it after that.
My Egyptian Mau had some raw food (meat) 3 days ago and was puking the following morning.
If you lived closer to me (London), I would've let you have a few packs of frozen raw meat to try out on your cats, for free. I'd rather it go into a cats belly than in the bin.
If you want to experiment with raw meat, try getting frozen minced rabbit - I used to buy this when my 2 were very young, from Pets At Home. This stuff is cheaper than the meat I linked to above. If your cats are happy with it, then you can buy the stuff from Natural Instinct. You can also try going to your local butcher and get the cheapest cut of meat from there.
I always try and give my cats the highest quality food I can afford, but in most cases, they don't like it...except for Applaws Wet food in a can (this stuff is uber high quality and my Bengal salivates over this stuff ... yes even the fussy Bengal).