Has this puppy been to the vet's yet? Most puppies are born with worms and if these are not treated they will certainly prevent them from gaining weight.
What are you feeding, how much and how often? Growing puppies need a quality puppy food, not something bought in the local grocery store. Depending on their breedm at eleven weeks they may need up to four cups per day, divided into three or four feedings. Quincy is 15 weeks old and he is eating SEVEN cups of Taste of the Wild puppy food each day. He is NOT overweight!
Puppies are growing fast and should not be fat!!
My first suggestion is to get this puppy to your vet, bring a stool sample to be checked for worms, and discuss his weight and feeding practices with your vet.
None of us here can see your puppy so we cannot tell what you consider skinny. Only your vet can do this.

Quincy answered on 11/7/12. Helpful? / 0