Here's a link with lots of info. The site is not attached to or funded by any foods, raw or commercial, just has lots of info.
Dof food info
The first three ingredients in Purina Fit n Trim is: ground yellow corn, soybean hulls and corn gluten meal. Hmmm, when was the last time you saw a dog grazing farmland /forums/images/graemlins/tongue.gif Obviously the way it is keeping the pooch trim is by not giving him anything he can actually digest and get value out of. I've always been a believer in just feeding less food.
Lots of dogs get along fine on low cost foods and owning a boarding facility I see it every day, but many of them show signs of not being in the best of health either, such as runny eyes, dry skin, dull coats, licking their feet all the time... all signs that can mean allergic reactions to food, but they ARE old, so they're getting by.
I have seen first hand dogs switched to a better food, Canidae in this case because it's the food I choose to sell, whose owners have told me that they wish they hadn't switched because of the increased energy levels in their senior citizen dogs. I have seen dogs start growing hair back in bald spots, get the shine back in their coats and I have had customers notice the same things and tell me.
Not to mention that you really can feed less food if it's better quality (meaning a high digestabilty rate, what goes in comes out in much smaller quantities). I board a GSD that went from 8 cups of Puppy Chow a day down to 4 cups of Canidae a day. You don't think there was less to scoop, too /forums/images/graemlins/shocked.gif You might not see any physical difference in this dog because he's young now, but it's the long term effect your looking for. The same as in people's diets, but I do admit, given the choice of eating chicken wings everyday or grilled chicken breast... I'll take the wings /forums/images/graemlins/grin.gif