Roy, if your Schnauzer is overweight, then you can try out this dog food:
http://www.1stchoice.ca/en/nourritur...trolepoids.php
It's really good in controlling the weight of your furkid. The downside is it's hard to find and expensive.
A cheaper alternative would be to limit your meal feeding to once a day and a giving smaller portion. In between meals, you can give it some meat based dog snacks or those chewy bones that are high in fibre.
Also a walk in the park every evening will keep your dog happy, healthy and back into shape at no time.
Good luck!