Heard some woman at the supermarket yesterday obsessing over the number of calories in some crackers. Made me think of this:
Let’s say there is a person whose caloric intake is 2700kcal per day, which is quite the likely number. 2700kcal/day makes a total of 1000000kcal per year. That’s 10 million kcal in a decade or roughly 12 tons of food.
For a person to keep his weight within 5kg in the course of a decade he must have an accuracy in controlling energy intake and expenditure of 0,4% or 11kcal/day.
Having this kind of accuracy is impossible. 11kcal is the equivalent of a medium sized fart. What this shows, is that it is highly unlikely that energy balance is matter of cognitive control. We cannot tell people to count calories because it rests on an assumption of an inhuman accuracy equivalent to that of a very, very accurate machine.