Great article/slideshow from health.com to remind us why portion sizes are important.  
There are many tips to help figure out how much food you are eating. Some people measure and weigh, while others use visual cues.  For example: a serving of meat should be 3-4oz.  This is about the size of a deck of cards, or the palm of your hand. By knowing approximately how large your portion is, you’ll be better able to judge the adjustments that need to be made. 

Use whichever method works best for you! You can even use smaller plates to reduce the amount of food you can fit in them if that works for you.  The main thing is to start paying attention and make changes towards a healthier you.

Health.com portion sizes