Experience with food gorging?

So, our 18 mo old FS is a big kid...he's 95th percentile for height and pretty much off the chart for weight at 32 lbs. Since coming to stay with us (almost 3 weeks ago) he has been introduced to a healthier diet. We were told that he was a picky eater but he isn't at all...I'm positive it was lack of exposure. Told that he doesn't eat meats at all, but he will eat meats and vegetables with no issue as long as the healthy food isn't competing with cheetos, pudding, and Kool aid. I digress.... Now the issue is the amount he will eat. I generally feed our kids an appropriate serving and then if they are still hungry they can help themselves to fruit and veggies. But this guy continues to plow through anything put in front of him. We have seen this before, although mostly in older kids...never in a kid this young. So, I guess what I'm looking for reassurance with is.... Is it alright for me to serve a toddler sized amount and cut him off? He will ask for more but isn't dramatic about it at all. He doesn't vomit, but has had two HUGE poop explosions in the morning, and as much as I love washing and sterilizing everything touching his crib...I'd rather avoid it. I'm rambling...but any tips, pointers, or just assurance that this is the right way to handle this would be great.