There is a fine line between dieting, disordered eating, and an eating disorder. Dieting when necessary by either minimally decreasing food and increasing exercise is not an eating disorder, and if you are very overweight, then under the supervision of a doctor it is normally fine to restrict intake a bit more. No matter how overweight a person is, most of the time, even under a doctor's supervision, a person shouldn't eat less than 1200 calories a day, and most of the time that amount would even be a bit extreme for a diet. With disordered eating, it is not really an eating disorder, but there is often lots of guilt surrounding food, and some behaviors that seem eating disordered in nature. This would include crash dieting, fasting but then eating a normal amount, or skipping meals at sometimes, but eating larger meals at others. An eating disorder is a mental illness that has to do with eating, which may or may not drastically affect weight. Binge Eating Disorder is when someone frequently eats very large quantities of food in one sitting. Bulimia Nervosa is when someone frequently binges, but then somehow "purges" or compensates for a lot of the calories they have consumed. Anorexia Nervosa is when someone restricts their intake to a minimal amount and refuses to maintain a healthy weight. This may or may not include purging. Because of this, anorexia is normally only diagnosed at a BMI of 18.5 or lower in adults, or below the 5th or 10th percentile for BMI in children. However, some doctors will diagnose at higher weights if someone is at an unhealthy weight for their body. For example, someone's body may naturally settle at a BMI 27 when not restricting and living a healthy lifestyle, but the person may have restricted and ended up at a BMI of 22 and is terrified of gaining weight. Depending on the clinician, they may or may not diagnose this as anorexia nervosa. Eating disorders that are clinically significant, but don't fit into Binge Eating Disorder, Anorexia Nervosa, or Bulimia Nervosa may be diagnosed with what is called Other Specified Feeding or Eating Disorder (OSFED). This diagnosis includes subthreshold bulimia and anorexia. People who binge and purge, but not at the frequency as seen in bulimia and people who have some traits of anorexia, but frequently aren't underweight even for their body type will likely be diagnosed with this eating disorder. It is the most common eating disorder, but the least talked about in part due to the fact that many people in the eating disorder world are "ashamed" of having OSFED because anorexia is seen as "winning" the battle of the sickest , which is ridiculous. I've been in treatment with people of all types of eating disorders. Each one is a mental illness that requires treatment, often by multiple professionals. Because of this if you or the people around you are concerned about your eating, I would talk about it with your doctor. Tests should probably be done to measure your physical health. It may be helpful to work with a treatment team, such as a doctor, dietitian, and counselor to coordinate your care. Either way, we on here can not diagnose you with an eating disorder. That is something to talk about more with your dietitian or counselor. I would get help as soon as possible though if you think you have an eating disorder. The longer you have one the harder it is to recover.