People routinely make poor choices, despite knowledge of negative consequences.

Anorexia nervosa is a serious and puzzling illness. Even as its clinical signs have become increasingly recognized, the mortality rate remains among the highest of any psychiatric disorder.

A highly stereotyped feature of this illness is the persistent selection of low-calorie, low-fat food, despite the individual's desire for change. The brain mechanisms underlying this persistent and restrictive eating disorder are unclear.

The researchers used functional magnetic resonance imaging--which tracks activity in the brain in real time--to monitor 21 women with anorexia nervosa and 21 healthy individuals while they made a series of choices about what food to eat. As expected, individuals with anorexia nervosa consistently chose fewer high-fat foods.

The brain regions they used to make those choices were also different: for individuals with anorexia nervosa, choices about what to eat were associated with activation in the dorsal striatum, a brain region known to be related to habitual control of actions.

Furthermore, activation in fronto-striatal brain circuits during the experiment predicted how many calories they chose to consume in a meal the following day.

These are the first data linking abnormalities in brain activity with the salient behavioral disturbance of anorexia nervosa, restrictive food choice.

http://www.nytimes.com/2015/10/13/health/extreme-dieting-of-anorexia-may-be-entrenched-habit-study-finds.html