Which set of behaviors and signs should raise concern for a possible eating disorder and prompt a referral for help?

Complete lack of any dietary interest combined with increased appetite and steady weight gain over a long period, exclusively in the absence of psychological or social changes.

Only minor variations in meal timing that last a few days, occasional skipping of dessert at social events without any psychological distress or caloric restriction, and stable body weight without functional impairment.

Marked weight change, preoccupation with food or calories, repeated bingeing or purging episodes, amenorrhea in females, excessive exercise, frequent sore throats or dental erosion, and social withdrawal.

Any isolated instance of overeating at a party or holiday meal, which always meets the threshold for an eating disorder and requires immediate admission to an inpatient psychiatric unit.