I think that anyone who overfeeds pets and young children is not only being abusive/neglectful, but also should get into some serious counselling until they learn how to show love and affection without showering the object of thier love with treats and fattening food. Obesity is just as dangerous, if not more dangerous than being underweight; it is linked to everything from diabetes and asthma to sterility and deformed offspring. It is known to result in heart disease and other serious conditions, and is a huge contributor of arthritis, slipped disks, and torn ligaments in many animals.
I have had to deal with several obese animals in my life. My amazon, my two parakeets, and my cat were all obese when rescued. While it can be hard to deny a pet tasty treats, and force him/her onto a restricted diet, the end result is worth it. My cat is still about 1lb overweight, but considering he was about 6lbs overweight, he's lost a massive amount - and is still losing. He has so much more energy now and his coat is gorgeous. The pudgy keets are also doing better on a healthy diet; they'd been fed only spray millet by the prev. owner and thus were vitamin deficient, nearly round, and very weak. One is still slightly heavy as he eats compulsively, but at least he can fly and isn't having trouble breathing. And my amazon's weight problem was a mix of poor diet and no exersize - what a tiny cage she was in when I rescued her!
What I'm getting at with this is, the fact that people let a pet become obese when it was perfectly healthy is absolutely abhorrent.