[LunarBerry]

I know this pain well >_<, thankfully my girl is not obese but she is a bit chunky and the vet said even though she's young (10 months) she just needs to lose a few pounds to help her luxating patellas. So far it's going pretty decent and I plan to get a pool so I can do hydrotherapy. It's getting my mother to not feed her so much that's been the problem (but now I think she's finally getting it) as she's the one that feeds all our dogs tons (and this is just with canned food, scraps and dog treats). Now I don't buy treats (for now anyways), and we feed an occasional veggie as a treat.
Have you ever thought to look into homecooking for your furbaby? I would of course ask either a pet nutritional or the vet for recipes/suggestions and some sites offer recipes for proper recipes such as this one.
https://secure.balanceit.com/
It gives you both the satisfaction of "hand" feeding you're furbaby fresh food and they get the taste and nutrition they need. You can also take comfort in knowing exactly what goes into their food. Other options is getting dog foods that are "fresh" or wet, there are plenty of good companies that offer stew-like meals I used wellness canned chicken, lamb, and/or turkey stews in the past and all my dogs love it. Just remember proper portions for the day.