I agree 100% with L. G. Your son does not need nighttime nutrition; he is getting up for comfort and out of habit.
Every parenting style is different when it comes to sleep training. Some use Sears method, or Pantley's "No-cry sleep method," while others use Ferber.
Ferber worked very well for us, and while it was rough the first 1-2 nights, it worked. We still need to re-train her every so often, but it's never like the first time we trained her.
I'm not saying you should use Ferber...like I said, every parent has their own style. Ferber just worked for our family. My point is, I think your child needs to be sleep trained in some way; the nighttime feedings are not necessary at this age.
We trained her NOT because we wanted our sleep, but because simply, she was old enough to sleep through the night and not need any nighttime nutrition. The nightly wake ups were out of habit and sooner or later, they need to be stopped. Just like you train a child not to pee on the carpet, not to throw food, etc.