Yea, portion size in US restaurants are 2 to 3 times what they should be. I have gotten in the habit of splitting my meals when they get to me instead of just digging in. It's amazing how much better I feel after the meals I do this at since I am no longer over eating JUST because it is there.
In NY, the chain fast food restaurants need to post the calorie information now. It really is eye-opening, when the so-called "value meals" have 1,500 calories or more --- practically an entire day of calories, in 1 lunch meal.
By nutritional standards, most restaurant meals really are double servings, or more.
Like a porterhouse steak, is really enough beef for 3-4 servings... but it's not unusual for a restaurant to serve an entire porterhouse as a single serving. (I grilled a few days ago, and we split a 1 1/4 pound porterhouse between 2 adults and 2 children).