Let's start with the moral of the tale, seeing is believing. If you could see the quantities of food you were consuming you would probably stop before you overindulged. Especially when you consider the fact that the stomach takes about 20 minutes of eating to register a sense of feeling full.
A recent study, published in the journal Perceptual and Motor Skills, illustrates this point brilliantly. A group of 52 graduate students (17 men and 35 women) were told they were being treated to "all you can eat chicken wings" while watching the Super Bowl. The waitresses were instructed to clear the dirty plates from only half of the tables. And...you guessed it; the folks at the tables that were cleared regularly ate more. On an average grad students at the clean tables ate 28% more wings than the grad students sitting at tables littered with chicken wing remains. So, I repeat once again, seeing is believing.
Fit's Tip: Don't eat directly from the bag of chips. Place a reasonable size portion in a bowl and snack from that. When the bowl is empty you know you have consumed a serving, instead of accidentally finishing off the entire bag.