The most common symptom or sign of an eating disorder is the distorted body image also known as body dysmorphia. Body dysmorphia occurs in both anorexia and bulimia.

Warning signs of eating disorders include:

• Several food and eating related behaviors may be altered. The person may skips meals, take tiny portions, refuse to eat with others, eats in ritualistic ways, chews food only to spit it out, and mixes strange food combinations.
• Another characteristic sign is shopping for groceries and cooking meals for the family while not partaking in them. Early signs include disgust with former favorite foods, stopping and eliminating fat from all foods taken, gorging on foods in secret and secret attempts at purging.
• Behaviors related to appearance and body image – The individual often shows early signs of fears of weight gain and obesity. They tend to start wearing baggy clothes and layers of clothes to hide fat or emaciation. There may be excessive obsession about clothing size, image in the mirror, hatred for all or specific parts of the body, especially breasts, belly, thighs, and buttocks and complaints about being fat even when they are not.
• Behaviors related to exercise - The person exercises excessively and compulsively. Athletic performance suffers over time due to lack of nutrition but the individual keeps up.
• Signs in thoughts and beliefs – There may be early behavioral changes that involve denial of anything being wrong. The individual often argues with those who wish to help and may then sulk or withdraw or throw a tantrum. He or she may have trouble talking about feelings, especially anger. They may become excessively irritable, cross, snappish, moody and touchy.
• Changes in social behaviors – Individuals may try to please everyone and withdraws when this is not possible. May present self as needy and dependent or as independent rejecting of all attempts to help. While anorexics are averse to sex, bulimics may engage in casual or even promiscuous sex. There may be drugs or alcohol abuse.
• Those with binge eating disorder may have any compensatory behavior e.g. they do not purge, use laxatives or engage in compulsive exercise. The episode is triggered by an emotional upset and not by hunger. The individual may shop or procure large qualities of food that disappears soon after. These patients are usually overweight or obese, even though persons of normal or average weight can be affected. They tend to eat rapidly, large amounts of food, feel the lack of control to stop eating, never feel satisfied or satiated, eat without hunger, are embarrassed. These individuals are often depressed. Women with Polycystic Ovary Syndrome (PCOS) may develop binge eating and bulimic behavior.
• Rumination Syndrome – the individual practices painless regurgitation of food following a meal which is then either re-chewed, re-swallowed or discarded.
• Food Maintenance Syndrome – This is seen in children in foster care and shows a pattern of aberrant eating behaviors.
• Female Athlete Triad – This is a combination of three features. There is an eating disorder along with loss of menstrual periods for long periods of time and decreased bone mineral density commonly in female athletes.