It helps to keep an eye -- literally -- on the size of your portions:
Researchers in Berlin set up a study where participants would eat in the dark, allowing the researchers to alter portion sizes without the participants knowing. In darkness, the participants—visually unaware of whether they had been given the regular or super-sized portions—ate all of the food with little change in feelings of fullness between those with the large or small portions. In contrast, those who were fed the same portions in a lit area reported feeling fuller sooner and ate less. They were able to gauge how full they should feel based on the size of the portion in front of them.(Source: Lifehacker)
