I've been overfeeding the girls. By a lot.
You'd think that with all my crazy-person charts of calories per cup, grams per cup, cups per bag, price per cup, price per dog per day and so on, that I'd have bothered to weigh the cups.
A cup of Nature's Variety is around 95grams. The so-called "cup" I use is 135g !!! At 2 "cups" a day, they've been getting almost an entire extra cup of food. Like 4-500 calories more.
I'm hoping this finally explains why River can never lose weight and Robin (40 lbs) won't gain weight with her constantly soft stool (even though she's fed the same as River, who is 70lbs). I just kept upping her food, when I should have been decreasing it.
So I guess the moral of this story is, if you have a kitchen scale-- actually use it as a scale and not as a pot stand.