Eating Disorders

Eating disorders are psychiatric conditions with the HIGHEST mortality rate of any mental illness. Anorexia nervosa (AN) is characterized by restriction of energy intake leading to significantly low body weight, intense fear of gaining weight, and distorted body image. Bulimia nervosa (BN) involves recurrent episodes of binge eating followed by compensatory behaviors (purging via self-induced vomiting, laxative/diuretic misuse, fasting, excessive exercise). Binge eating disorder (BED) involves recurrent binge episodes without compensatory behaviors. AN pathophysiology includes starvation-induced metabolic adaptations: decreased metabolic rate, hypothermia, bradycardia, hypotension, amenorrhea (from hypothalamic suppression of GnRH), osteoporosis (from estrogen deficiency), muscle wasting, lanugo (fine body hair as insulation), and electrolyte abnormalities. Refeeding syndrome is the most dangerous complication of AN treatment: rapid reintroduction of nutrition in a starved patient causes insulin surge, driving phosphate, potassium, and magnesium intracellularly, causing severe hypophosphatemia, cardiac arrhythmias, heart failure, and death. BN complications include dental erosion (perimolysis from stomach acid), esophageal tears (Mallory-Weiss), metabolic alkalosis from vomiting (loss of HCl), hypokalemia, parotid gland enlargement (chipmunk cheeks), and Russell sign (calluses on knuckles from self-induced vomiting).