[anonymously]

Maybe you are feeding him too much? As long as he has no medical issues and your vet approves, you could try feeding him one meal a day in the afternoon, then walk him every 2 hours and at bedtime, first thing in the morning.
Just leave fresh water. Same for your other dog.

PS: Check general guidelines for tips http://www.homeovet.net/dynamic/php/downloads/dog-c8470f2c75dbe4b683205c3919ee2310/dog_diet_complete.pdf