You can also put a tennis ball in the bowl so they have to work around that. But how much you feed depends upon the dog's activity level, their metabolism, if they're going through a growth spurt, as well as the brand of food so that can't really be answered "matter of fact". I will say though, you need to pay careful attention to a dog becoming overweight, and someimes "tough love" is a must. If I fed my female everything she wanted to eat she'd be back up to 70+ pounds and be severely overweight, so yes, as with human children, you just need to learn to say no. That does not mean starve them but if you know they don't need it, they're a good weight and growing, then sometimes "no" is the nicest thing you can do.
Tyson, white, 4 years, Boxer & Thor, 2 year old GSD
Tiger and Raven, kitties, 10 and 11 years
Erin flashy fawn, Lucas, Flashy Fawn, Boxer angels, RIP 11-29-10 and 8-22-07