I'd heard that human food is better for dogs than dog food is...
Junie's weight gain is surprising to me. I've given her treats but I didn't give her a large amount. eg. One bite of a hamburger (after I broke it off), one slice of ham, etc.
I grew up on a farm and we never got 'dog food' except when they were puppies. They ate what we ate and they never got fat. The only thing I can think of is, being on the farm it's possible they worked out more by running around in the fields. Perhaps that's why I didn't think much of giving her a piece of steak.