The portions of what you are eating come in to play into the amount of calories you are eating. If you look at the back of a can of soup and it says that the can holds 2.5 servings and then the calories listed are at 110 calories per serving, that can of soup you just ate was really near 300 calories. Now if you look at that bag of chips, it says one serving size is 14 chips, and these 14 chips have 200 calories. How many chips did you eat? Portion control and learning about calories is going to really help your diet overall.
In eating out and calories you will find that the posters on the wall are going to be set out in a similar pattern as what the can of soup has or those chips. While it may tell you that a serving of fries (small) has 500 calories the poster may not tell you what the large fry has in it. A portion of meat in your daily plan should be no bigger than the palm of your hand, but if you were to take a look at the triple cheese burger that your friend was sitting beside you eating, that is way more than one should eat at a sitting. Portion control while remembering to look at the calories in what you are eating will help you overall lose weight and to keep that weight off.