I found these websites. Maybe you could try this dog food, its supposed to help w/ weight loss.
http://www.healthypetnet.com/Healthy...lname=10075847
This website offers a sample pack of that food for $3 w/ free shipping.
http://www.petprokennel.com/site/532373/product/K9-3pak
This Canine Zone dog food is supposed to be really good. Hope this helps!