My 3 year old is smarter than me

My wife and I try to feed our boys nutritious meals and snacks. Low sugar, no saturated fats, low salt, organic fruits, whatever we can do to find the best foods for our boys. I have been trained well to always read the labels and not be fooled when the package says "0 gram of trans fat per serving." Apparently the manufacturers are rounding to zero for very small serving sizes, because there are trans. fats in the package, just not enough to quantify per serving. We allow them to have sweets, but not too much. Our rationing of sweets has of course resulted in creating sweet-toothed monsters in our boys. Whenever, they are at a birthday party or after game snack, to say they binge on sweets would be an understatement. My wife and I are trying to find a healthy balance, so that we do not go overboard.

Today my 3 year old wanted to have a juice box. Well, I told him that he could only have one today and that he would need to eat lunch first. he agreed and ate a good sized lunch. In the afternoon he was whining and wanted to have another juice box. I mentioned to him that he already had one and that we agreed to one a day. I also made up a story, as parents are prone to do, that if he had another one it would make his tommy ache. My 3 year old, clearly smarter than I am, said "I want my tummy to ache." I couldn't win the argument, so I gave him another juice box, after which he said to me, "hey my tummy feels fine."