houtsdg & AJ Nav......one of my GSP's was ALWAYS very skinny no matter how much food we fed him. When he was a pup we always fed him the recommended amount and we thought he was too skinny. So we started increasing the amount of food we gave him and no matter how much (basically as much as he could eat) he was always skinny. And this went on when we were hunting him and even in the off season. He's now 4 years old and up until last year he was still "too skinny." Over the past year he has really filled out and now weighs around 80 lbs and is solid muscle and we basically feed him as much as he can eat (which is about a coffee can and a half plus a can of canned dog food)! However, we try to run our dogs for about 10 minutes every day to keep them in shaped when they're not hunting. Based on this experience I would say that it depends on the dog and its metablism and to just feed it as much as it will eat and if you notice the dog is gaining too much weight then just back off the amount of food you give it.