I was feeding Delgado twice a day and he couldn't eat more then two cups in a meal without him getting diarrhea. He went through a growth spurt where he was eating 4.5 cups of Fromm LBP (two cups twice a day plus a snack of half a cup in a treat ball at night) not including treats and was still gangly. He started filling out around a year and is still bulking up now in a good way.
Try spreading the food over more meals and see if the diarrhea stops, if it continues I would look at switching foods as that might be the issue. It's best for them to gain weight slowly so I wouldn't worry about him gaining 5 lbs this week or anything, a slow steady gain in much better.
Jasmine - Female Miniature Poodle - born Aug 15, 2010
Loker Delgado Von Stalworth - Male GSD - born Jan 26, 2012
Koda & Zazu - 5 year old male cats
Alex - Male Cocker Spaniel (rescue) - RIP Cuddlebug 2007-2010