Matsa and Anderson next looked at data on individual eating habits from a survey conducted between 1994 and 1996. When eating out, people reported consuming about 35 percent more calories on average than when they ate at home. But importantly, respondents reduced their caloric intake at home on days they ate out (that's not to say that people were watching their weight, since respondents who reported consuming more at home also tended to eat more when going out). Overall, eating out increased daily caloric intake by only 24 calories.
Appetite is an evolutionarily wired signal on par with pain; urging obese people to just eat less is like urging someone to tough out root canal surgery without anaesthesia. Every day.
I am pretty convinced by Seth Roberts' theory that the hyperpalatability of modern processed food is kicking up everyone's set point. (Well . . . almost everyone). But another of the paper's findings, that closeness to fast food doesn't seem to make you fatter, does seem to cast a little doubt on this.
It certainly casts doubt on the effectiveness of labelling, or a "fat tax". I'm not against putting calorie counts on fast food; I just don't think it will do any good. Peoples' calorie consumption is dictated by their appetite. Which makes sense, if you think about it; it only takes a swing of ten calories a day (about five tic-tacs) to gain or lose a pound over the course of a year. If our appetites weren't doing a surprisingly good job of regulating our weight, we'd all be bone thin or morbidly obese.