I had a Lab mix years ago that was quite long lived for the typical life span of a larger dog. She was a big Al type binger that would eat any food put in front of her, then go steal the other dog's food when she was done. She had to be strictly controlled in her meals. I figured out there was about a 5 pound difference between getting around well, and struggling. She was roughly 90#s at 17 years of age. She went up and down 2 flights of stairs on her own, as well as regular walks, right up until her last day.
Amber's dog as at that age where she should start to be put on food for a less active dog, and kept at a healthy weight for quality of life. I'm not surprised a fat tub of guts like Amber would have a fat dog. If she has any love for that dog at all, she'd do her level best to see that she was health and exercised.