The Differences Between Anorexia and Bulimia

The differences between anorexia and bulimia are numerous, but they're both severe and lethal. Here's how to distinguish between them.

Written and verified by el biólogo Samuel Antonio Sánchez Amador.

Last update: 04 June, 2023

Eating disorders (EDs) are much more common than it seems in general society. Although efforts to achieve bodily acceptance are increasing, certain population groups remain vulnerable to the gaze and judgment of others. Do you want to know what the differences between anorexia and bulimia are?

Due to both social and genetic reasons, a person may be more or less prone to developing an eating disorder throughout their life. In any case, women are much more likely to suffer from these disorders than men, as until recently (and still today) unattainable body standards were expected of many of them. Fortunately, this trend is beginning to change.

Despite social advances, it’s estimated that at least 4% of women worldwide suffer from anorexia at some point in their life (while 2% suffer from bulimia and 2% from compulsive eating). Although this pathological group is surrounded by a stigma, we can’t forget that it represents an obvious social and health problem. Here, we’ll show you the differences between anorexia and bulimia.

What’s an eating disorder?

The American Psychiatric Association (APA) defines an eating disorder (ED) as “any condition characterized primarily by a pathological alteration of attitudes and behaviors related to food.” The patient may eat too much in short intervals, eat too little or nothing, vomit food, or ingest inedible substances.

Types of ED

Despite the implications of these disorders, it should be noted that obesity isn’t among them. To date, these are the most well-known EDs and those most cited by specialists in psychiatry:

• Anorexia: The patient has a distorted image of themself and restricts their caloric intake to the point of starvation. The severity of the condition can be estimated according to the body mass index (BMI), although more and more factors specific to the patient are taken into account.
• Bulimia: People with bulimia eat excessive amounts of food and then purge their digestive system, either by vomiting or using laxatives. The severity of the condition is calculated according to the number of weekly compensatory behaviors.
• Binge-eating disorder: As the Mayo Clinic indicates, patients with this disorder eat unusual amounts of food at a certain time and feel that their eating behavior is out of control. Unlike bulimia, in this case, the person doesn’t vomit.
• Pica: This is the repeated intake of non-nutritive substances. Paper, soap, hair, and other items are the most common materials. This disorder is not unique to humans, as several animals manifest it as well.
• Rumination: Patients with this disorder chew food, but then spit it out or regurgitate it (without actually vomiting).

There are some more EDs, which are included in the group of o ther specified feeding or eating disorders or OSFED. All of them report a conflictive relationship with food, either due to excess, defect, or atypical behaviors related to eating.

The differences between anorexia and bulimia

Although both are eating disorders, it should be noted that there are many differences between anorexia and bulimia. We’ll explore them below, always consulting professional sources and with medical data in hand. Keep reading.

1. They’re different disorders

Anorexia, known clinically as anorexia nervosa, is a disorder characterized by the attempt to lose weight to the point of starvation. People affected by this condition eat much less than expected for their weight, age, and height, as indicated by the United States National Library of Medicine.

Some of the symptoms derived from this clinical picture are the following:

• A body mass index (BMI) that’s much lower than expected for the patient’s age and height.
• Amenorrhea: The cessation of menstruation occurs in women of reproductive age with a very low amount of body fat. As the patient isn’t prepared for pregnancy, their reproductive system shuts down.
• Chronic fatigue and insomnia.
• Constant and very rapid weight loss that can’t be explained by another disorder.
• Slow (bradycardia) or very fast (tachycardia) heartbeat and hypotension.
• Halitosis (bad breath).

On the other hand, bulimia is defined by the APA as “a disorder that involves recurrent episodes of binge eating (that is, discrete periods of uncontrolled consumption of abnormally large amounts of food) followed by inappropriate compensatory behaviors (self-induced vomiting, misuse of laxatives, fasting, excessive exercise).”

Some of the most obvious symptoms of this disorder are the following:

• Chronic gastric reflux secondary to constant self-induction of vomiting.
• Electrolytic imbalances. These stem from continuous emesis and can lead to abnormal heart rhythms, heart attacks, and even death.
• Inflammation of the esophagus (esophagitis) as a result of the habitual rise of acids through this conduit.
• Peptic ulcers (open lesions in the digestive environment). They can be gastric or duodenal.
• Oral trauma and lacerations caused by the effort exerted by the fingers when vomiting and by the rise of acids in the mouth.
• The erosion of tooth enamel (yellow and small teeth).
• Constant fluctuations in weight.

The symptoms are relatively different

The first of the differences between anorexia and bulimia is clear: In the first disorder, the patient eats much less than normal (or doesn’t eat at all), while in the second, they take in food excessively, but in some cases, throw up their stomach contents.

Anorexia is always associated with chronic weight loss, although bulimia often appears with recurring fluctuations in body mass index. At the same time, bulimia presents much more evident esophageal and oral symptoms than anorexia, as these structures come into contact with stomach acids when they shouldn’t.

2. Their diagnostic criteria are different

The Diagnostic and Statistical Manual of Mental Disorders (DSM) is published from time to time by the APA to collect diagnostic criteria for all psychiatric disorders. Below, we want to describe each of the parameters that professionals use to characterize bulimia and anorexia. Keep reading to find out what they are and compare the criteria for both.

2.1 The Criteria for anorexia

The DSM-5 published in 2013 includes the following criteria to detect anorexia:

1. The restriction of food intake leading to weight loss or inability to gain weight. This results in a “significantly low body weight” compared to what would be expected for the person’s age, sex, and height. BMI is a good initial indicator, although factors more specific to the patient are increasingly being used.
2. Fear of gaining weight.
3. A distorted view of oneself by the patient. For example, it’s common for anorexic people to think that they’re fat (when they’re not) or that they can gain too much weight from eating a single meal. Sometimes the patient will believe that there’s no problem with being underweight and will deny the obvious reality.

There are 2 main types of anorexia: Restrictive and binge/purgative. The first variant is the one that’s typically associated with anorexic conditions and, in this case, the patient doesn’t have binge episodes. On the other hand, purgative anorexia requires the person to resort to compensatory behaviors when they eat large amounts of food.

Anorexia can also be categorized according to the severity of the condition as follows:

• Mildly severe: The patient’s body mass index (BMI) is greater than or equal to 17. Keep in mind that the optimal BMI is between 18.5 and 24.9, although figures above or below this spectrum aren’t always considered pathological.
• Moderately severe: BMI is between 16 and 16.99.
• Severe: BMI is between 15 and 15.99.
• Extremely severe: BMI is less than 15.

2.2 The criteria for bulimia

Professional clinics cite the following criteria to diagnose cases of bulimia:

1. Recurrent episodes of binge eating characterized by the following: 1) Eating in a period of 2 hours more than expected in a similar situation in the case of a non-pathological condition and 2) feeling that the patient can’t stop eating or control what (or how much ) they eat.
2. Inappropriate compensatory behaviors to avoid weight gain. Self-induced vomiting is the most common, but misuse of laxatives, diuretics, or other medications is also conceived. Fasting and excessive exercise are also compensatory behaviors.
3. These callsigns occur at least once a week for 3 months in a row.
4. Self-assessment of the patient’s weight and body doesn’t correspond to reality.
5. The alteration doesn’t occur exclusively during episodes of anorexia nervosa.

Bulimia is also categorized according to its severity. These are the existing variants:

• Mild: The patient shows 1 to 3 compensatory episodes during the week.
• Moderate: The patient presents 4 to 7 compensatory behaviors in 1 week.
• Severe: 8-13 compensatory episodes per week.
• Extreme: 14 or more weekly compensations.

2.3 Diagnostic differences between both pictures

There are several differences between anorexia and bulimia from a diagnostic point of view. Anorexia always implies a clear weight loss (although not dictated by the BMI in any case, in what’s expected for the person in particular), but bulimia doesn’t. It’s normal for a bulimic person to lose weight, but also to gain weight when avoidance behaviors are stopped for a while.

At the same time, bulimic patients show a clear lack of control when it comes to eating, although anorexic patients have clear regimens. Those with anorexia exercise constant “self-control”, as they’re capable of not eating for long periods of time regardless of the situation. It should be noted that this general rule doesn’t apply to purgative anorexia.

3. Different epidemiological figures

As indicated by the Statpearls medical portal, anorexia is much more common in women than in men. The prevalence is 0.9 to 4.3% in females and 0.2 to 3% in males. Besides sex, this condition presents as a risk factor among those who have previously suffered obesity, other concomitant disorders, sexual abuse, and certain personality traits.

The ranges of bulimia are quite fluctuating, varying between 0.1% and 1.4% of men and between 0.3% and 9.4% of women. In any case, the upper limit of the average is found at 4% of the female population throughout their lives. Interestingly, it appears that this disorder is much more prevalent in cities compared to rural areas.

As you can see, anorexia and bulimia have similar epidemiological ranges. Bulimarexia is a condition that combines features of both disorders and is relatively common in people with EDs, but it doesn’t present any of the 2 disorders to their maximum extent. The epidemiological figures for the latter aren’t as well researched.

4. Associated mortality rates

Unfortunately, it’s ultimately necessary to talk about death rates because anorexia is considered the most deadly psychiatric disorder of all, even above major depression and schizophrenia. It’s estimated that 5% of anorexic people die in a variable period due to consequences associated with the disease, such as the following:

• Endocrine system: Loss of menstrual period, infertility, hypoglycemia, and decreased bone calcification.
• Gastrointestinal system: Constipation, abdominal pain, intestinal bloating, and more.
• Heart: Mitral valve prolapse, abnormal rhythms, failure, cardiac arrest, and ultimately death.
• Other associated problems: Anemia, hair loss, muscle loss, and effects derived from chronic and constant malnutrition.

On the other hand, the mortality rate of bulimia is estimated at 3.9%. In any case, the general prognosis is somewhat better than that of anorexia, as in this case, 50% of patients are completely cured 10 years after receiving the diagnosis. On the other hand, more than 20% of anorexic patients develop a chronic and constant disease over time.

The differences between anorexia and bulimia: 2 very dangerous disorders

The differences between anorexia and bulimia are multiple, but unfortunately, they share an essential character: Their lethality. As we’ve said, the first of the aforementioned disorders is the deadliest psychiatric illness on record to date, claiming the lives of approximately 5% of patients who suffer from it. In addition, in 1/5 of the cases, it’s never cured.

Although the overall vision seems hopeless, know that you’re not alone. If you’ve seen yourself reflected in the above article, don’t underestimate what you’ve learned, and don’t try to downplay your symptoms. If you suspect that you have an ED, it’ll most likely be confirmed during a visit to the psychiatrist.

If you suffer from one of these disorders, don’t throw in the towel: Constant therapy (2-3 hours a week or more), hospitalization in severe cases, and the intake of certain drugs (such as selective reuptake inhibitors serotonin) can help you a lot to overcome your disorder.