There are several reason why eat more and take more calories when you eat out. First you cannot control the portion of the mael when you eating at the restaurants. You just order and eat how much they brings you in a portion. Most of the time you regret that you eat that much. But this is unfotunately a habit of most of us, eating what we have through the end of the plate. Secondly, you cant control the ingridients of the meals. On the contrary, you can control the fats and other ingriedients according to the your calories goals. Scientific sears proves that people eating out are taking 150 calories more at average.