How much food should i eat? part 2

Help Yourself: The Truth About Serving Sizes
Look at the label on any product package and you'll see a nutrition information section that gives a serving size for that food. Contrary to popular belief, this serving size is not telling you the amount you should be eating. It's simply a guide to help you see how many calories and nutrients — as well as how much fat, sugar, and salt — you get from eating a specific quantity of that food.

Sometimes the serving size on a package will be a lot less than you are used to eating. In some cases, it's perfectly OK (and even a good idea) to eat more than the serving size listed on the package. For example, if you're cooking frozen vegetables and see the serving size is 1 cup, it's no problem to eat more because most vegetables are low in calories and fat yet high in nutrition.

But when it comes to foods that are high in calories, sugar, or fat, the serving size can alert you that you may be getting more than is healthy. If you buy a 20-ounce bottle of soda and drink it all at once, the amount you consumed is 20 ounces. But if the label shows the serving size is 8 ounces, not only did you have 2½ servings, you also had 2½ times the listed calories as well as 2½ times the sugar.