We all know to lose weight we need to eat fewer calories than we burn. It is simple math. However, getting into that calorie deficit is not always so simple.
While we might think we know how many calories we consume in a day, it is worthwhile to really track what you eat, calorie wise for an entire day. You might just be surprised (as I was that someone could consume 2000 calories in 4 minutes last night on "The Biggest Loser") by the total number of calories consumed, and that surprise could be educational. It is a nit picky activity writing down every single calorie, that is why I only suggest doing it for one day. I consider this activity intense food journaling, but what a great learning tool. Write what you eat as well as the calories consumed, and try to be as accurate as possible.
Read the nutritional labels of the foods you are eating and pay attention to portion sizes too. If the food is not packaged, here are a few sites to help you with the numbers: