There is an interesting phenomenon that has happened over the past few years in food outlets, where portion sizes have grown gradually to the point where food is now being served at more than double the portion size for a "normal" or healthy meal.
The sad thing is that a lot of people see the new sizes as being standard and it is sometimes hard to not get sucked into eating more than one normal serving without even knowing it. I used to go along with this at times, so I can't criticize, especially as I am hardly skinny myself. :P
I won't write much about it, but just tell a story from the weekend when we really noticed the difference.
My husband went to the bakery to buy bread (I grew up rural, so having a bakery that makes nice bread one block away is wonderful). He bought one serving of vanilla slice for us to share as a treat. I took one look at it and knew I didn't want to eat half, so I thought I would be conservative and cut my half into one further half so that I was eating one quarter of the original size and more in control of the portion.
I finished the quarter, but I could not have eaten any more. My husband ate a similar amount of his half, and put the rest into the fridge for another day. The thing that frightens me is that we bought ONE serving, and two grown adults could only just finish HALF of it. We couldn't have eaten more if we had wanted to.
It reminds me of the local noodle place, where we will often buy a large serving each, and then eat it over the space of three meals. We eat well, and aren't stick-thin. But there must be people out there who eat food in these portion sizes and think it is normal, and then wonder why they put on weight when they are not eating any more than the "one" meal or the "one" serving.
Modern eating really is filled with traps for the unwary, particularly if you were raised to finish what is on your plate, and it has taken me years to realize that you can ignore the serving size that you are given and still be full, and that bigger is not better. :)