Signs of an Eating Disorder - as part of the expert series by GeoBeats. While most people would think that low weight would indicate an eating disorder, that is not always the case. Any kind of obsession with food, whether it is obsessing about how many calories, or carbs, or fat grams are in a food item, weird food habits, such as cutting your food in little pieces, or pushing it around the plate, being obsessed with exercising continuously, body distortion, thinking you are overweight when you are actually a normal weight, or you are underweight, mood swings, losing your menstrual period, loss of sexual desire, rapid weight loss, they are all good signs of an eating disorder.