system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why are the recommended portion sizes on food so small?

For example, I bought a average size chocolate bar from the store today and the portion size on the back said half of the chocolate bar. I've never never seen anyone eat just half a chocolate bar.
gpt
Laws require companies to put calorie labeling on packages, so that people can tell how bad for them something is.  Lots of studies have determined that a "splurge" item like a candy bar sells best if it has 200-250 calories in it.  So, the companies started making the bars smaller.  People didn't like that, they felt they were getting cheated (mostly because the price didn't go down).  So, the companies started making bars the regular size, and then dividing the calories by 200 and saying 2.5 servings per bar.  This is legal, and it leads ot the most sales.  No problem.