Anorexia nervosa
A disorder in which fear of weight gain drives deliberate energy restriction to a degree that starves every organ system, and where the starvation state itself entrenches the cognitive distortion that sustains it.
First principles
The core lesion is a distorted cognitive appraisal of body weight and shape, not appetite
Anorexia nervosa begins with an intense fear of weight gain and a disturbance in how body weight or shape is experienced: self-worth becomes disproportionately tied to being thin. This drives deliberate restriction of energy intake relative to requirements, deliberately maintained below a healthy weight for age, sex and height. Crucially the drive is cognitive and motivated, not a loss of appetite (unlike depression), which is why patients can describe intense hunger yet still refuse food: the restriction is enforced top-down by the overvalued belief, not driven by the body's hunger signals.
Educational content pending clinical review. Not medical advice.