There is a Yale University study which proves that the number of calories we consume is not the only thing affecting our eating choices. There is a hormone in our bodies called ghrelin that tells our brain when we are hungry, and in this study, they tested whether our ghrelin levels are affected by our conscious brain.
There were two groups of participants both given the same 380cal shake. However, group 1 was told they were given a "sensible shake" that was just 140cal and group 2 was told they were given an "indulgent shake" that had 620cal.
When ghrelin levels were tested after consuming the shakes, group 2 with the "indulgent shake" had much lower levels of ghrelin than their "sensible" counterparts. This means that the group who consumed the "indulgent" shake were not feeling as hungry after consuming the shake as the "sensible" group.
So what does this mean for your eating habits? If you feel like you ate a "sensible" or "light" meal, your conscious will trick your body into releasing the hunger hormone, ghrelin, faster in order to eat sooner. On the flip side, does this mean you can convince your body you ate a calorie-dense meal? Obviously so! Next time you eat a light or sensible meal, convince yourself that it is more calories than it is, and maybe you will find yourself eating less throughout the day.
MIND OVER MATTER IS FOR NUTRITION TOO!
You can find the full study here: http://aionfitness.com/pdf-files/MindOverMilkshakes.pdf