Molly from 9 years on was very thin, even though I was sneaking her extra stuff when the "boss" wasn't looking, and since I free feed, she had all the food she could eat, and since she's gone, I found out she was eating a LOT of food, dry, canned, and off the table, but she still was "very thin" at best. It was good for her bad hips, but King looked almost fat (52 pounds isn't fat) next to her, and a couple of people asked me if he was "letting her eat". He only kept her from eating a few minutes at most. Since she's been gone, 2 inches in their dish lasts King days (I toss it if it's there overnight). The amount of turd cleanup has dropped by at least 75%. I think when some dogs get older, like people, they just get kind of thin, no matter how much they eat. A friend of my mom's is like that, eating cookies by the dozen every day, on top of quite a bit of regular food, ice cream and candy, and weighing a whopping 100 pounds at 5'7" (she used to be almost 5'10" and weighed 140 or so until she got into her late 60's). She walks 5 miles a day, and is very healthy at 84. her 86 year old hubby looks like her son though, she isn't even recognizable from when she was young, but her husband looks like an old version of himself from 50 years ago, Fred Flintstone with 50/50 grey and black hair.