yh i used to give new food and treats every day and hardly any veg or fruit.
But since i've changed dramitcally and now my hammys find something to look forward too on a routine.
I feed about 2-3 tablespoons of food every other day and i do not fill it up until the majority is gone (although i was away for a night and my sister decided that she would fill up the whole bowl even though i gave strict instructions, you'd think an older sister would know better
)
Then veg or fruit about 3 times a week, thumb tip sized for syrian and fingertip sized for robo.
Then treats only about twice a week, that being: millet seeds, yogurt drops, rodent marbles, cracker or bread.
Sorry to ramble just thought it'd help if you got an idea of others routine
For weighing try givving them a bit of spagetti which takes a bit of time to eat so you can read the weight.