What Is Anorexia Nervosa? How Can A Dietitian Help?


Anorexia nervosa isn’t the most common eating disorder. But it’s the oldest and (arguably) most talked-about diagnosis. And because of the complex mental, physical, and emotional aspects of the disease, anorexia nervosa treatment can seem pretty scary. As an eating disorders and anorexia nervosa dietitian, here’s what I think you need to know about the disease, plus how nutrition counseling can help.

What is anorexia nervosa?

The National Eating Disorders Association (NEDA) describes anorexia nervosa as an eating disorder characterized by weight loss or inappropriately low weight, food restriction, body image concerns, and sometimes compensatory behaviors like excessive exercise and purging.

The most recent Diagnostic and Statistical Manual of Mental Disorders (the DSM-5) outlines this criteria for anorexia nervosa:

  1. Restricted calorie intake leading to a significantly low body weight in the context of age, sex, developmental trajectory, and physical health. 
  2. Intense fear of gaining weight or being fat, even though underweight.
  3. Disturbance in how one’s body weight or shape is experienced, undue influence of body weight or shape on self-worth and self-evaluation, or persistent lack of recognition of the seriousness of the current low body weight

In order to be diagnosed with anorexia nervosa, all three criteria must be met. 

What is “significantly low body weight”?

The current weight criteria is a point of contention among eating disorder experts (me included). It’s possible to have a severe restrictive eating disorder without a “significantly low body weight”. But, a “significantly low body weight” is a required criteria for an anorexia nervosa diagnosis

For adults, “significantly low body weight” in anorexia nervosa means being less than 85 percent of ideal body weight for height (which can be calculated using different formulas), or at a body mass index (BMI) under 18.5.

For children and adolescents, “significantly low body weight” in anorexia nervosa means being less than 85 percent of expected body weight for age. This varies from person to person, and it’s determined by looking at the person’s growth charts.

People who don’t meet this weight criteria but meet the other criteria for anorexia nervosa will be diagnosed with “atypical anorexia.” Ironically, “atypical” anorexia is far more common than anorexia nervosa. It’s still a serious and potentially life-threatening eating disorder, and falls under the other specified feeding and eating disorder (OSFED) diagnosis.

What are the signs of anorexia nervosa?

Although it’s impossible to diagnose someone with an eating disorder just by looking at them or observing their behaviors, there are common signs and symptoms of anorexia nervosa to look out for. These include:

  • Significant weight loss (often in a short period)
  • A preoccupation with weight, food, macronutrient or calorie tracking, and dieting
  • Dressing in big clothes or lots of layers to hide weight loss
  • Feeling cold often, or wearing lots of clothes or blankets to stay warm
  • Comments about feeling fat or hating their body despite recent weight loss
  • Stomach pain, constipation, or other digestive issues
  • Tiredness or lethargy
  • Eating very little but denying any hunger
  • Food rituals, like excessive chewing, only eating at certain times, playing with food on the plate
  • Cooking for others without eating themselves
  • Making excuses to avoid eating
  • Burning off any calories eaten through exercise
  • Exercising religiously, regardless of tiredness, sickness, weather, injury, or anything else
  • In menstruating females, a loss of their period
  • An intense fear of gaining weight of being fat
  • Withdrawn demeanor, and/or retreating from relationships
  • A strong need for control around food and other aspects of life, with limited or no flexibility
  • Dizziness
  • Fainting, typically caused by orthostatic hypotension, a rapid drop in blood pressure
  • Abnormal blood work, like low iron (anemia), low thyroid hormone and other hormone levels, low potassium,and low blood cell counts
  • Trouble sleeping or sleeping too much
  • Dry skin, dry and brittle nails
  • Loss of head hair
  • Fine hair growth on other body parts (this is called lanugo)
  • Weakness and poor immune function (which can lead to being sick often

What causes anorexia nervosa?

Like all eating disorders, anorexia nervosa is caused by a variety of factors. The causes can and do vary from person to person. There’s a genetic component to anorexia nervosa, but environmental and mental health factors also play a huge role.

The media can certainly increase someone’s risk of anorexia nervosa. Our culture constantly tells us that it’s important to be thin and stay thin. This can increase the likelihood of dieting, which drastically increases someone’s (particularly an adolescent’s) risk of an eating disorder.

Anorexia nervosa can also happen alongside other mental health issues, like depression, anxiety, schizophrenia, bipolar disorder, and obsessive-compulsive disorder.

If you or your child is struggling with anorexia, it’s important to know that it’s not your fault. Eating disorders are complicated and have so many causes. Many are out of our control.

What are the health consequences of anorexia nervosa?

All eating disorders have serious emotional, mental, and physical consequences. Anorexia nervosa is no exception.

Anorexia nervosa leads to malnutrition and too little body fat, which can lead to serious health complications. (Source.)

Cardiovascular complications

Bradycardia — slow heart rate

Dilated cardiomyopathy — a heart muscle disease that causes heart chambers to thin, stretch, and grow larger, which makes it hard for the heart to pump blood to the rest of the body

Electrolyte-induced arrhythmias — an arrhythmia (irregular or abnormal heartbeat) caused potassium levels that are too high or too low. In some cases, this can be fatal.

Hypotension — low blood pressure that can lead to fainting and other issues

Growth and development complications

Failure to thrive or stunted growth — slowed growth that doesn’t keep up with a person’s history of growth

Very low body weight and insufficient fat stores — this can lead to low energy, constant cold, weakness, and poor immune function

Muscle wasting — reduced muscle mass due to not enough protein and energy

Hormonal complications

Hypothalamic amenorrhea — low levels of sex hormones due to insufficient nutrition, which leads to the loss of your period

Delayed puberty — children who have not yet gotten a period or experienced the physical changes of puberty may not experience them until much later

Osteoporosis — related to hypothalamic amenorrhea; if estrogen and other sex hormone levels are too low for too long, it can decrease bone density (which is irreversible) and lead to increased risk of osteoporosis later in life

Digestive complications

Constipation — not getting enough food can slow and impact digestion to a point where someone becomes constipated

Gastroparesis — literally this means partial paralysis of the stomach. When the stomach is deprived of food and nutrients for too long, muscles stop functioning with their normal strength and it’s hard for the stomach to empty food into your small intestine at a normal rate. This leads to slower digestion and discomfort.

Brain and psychiatric complications

Brain atrophy — loss of neurons and the connections between them

Peripheral neuropathy — as a result of damage to nerves outside the brain and in the spinal chord (due to malnutrition), it causes weakness, numbness, and pain in other areas of the body. Usually it occurs in the hands and feet, but it can also impact blood circulation, urination, and digestion



Inability to focus

Insomnia — difficulty falling and staying asleep

Renal (kidney) and electrolyte complications

Hypokalemic metabolic acidosis or alkalosis — pH imbalance in the blood due to too-low levels of potassium, which can have serious consequences and sometimes be fatal.

Renal failure — kidney failure, which can sometimes be fatal and often leads to irreversible kidney damage that impacts the body’s ability to filter blood.

Refeeding syndrome — electrolyte imbalances (phosphorus, potassium, etc) that sometimes happen when a person starts eating after a long period of eating very little

How can nutrition counseling with a dietitian help treat anorexia nervosa?

Because anorexia nervosa is so complicated, it’s important that you have a full treatment team. This will definitely include a primary care provider, therapist, and dietitian. It might also include a psychiatrist, an occupational therapist, and other healthcare providers that can make recovery easier.

Nutrition counseling helps people with anorexia nervosa to feed themselves adequately. This 2015 article gives a great overview of how dietitians treat anorexia nervosa. I’ll summarize some of the findings below.

A good dietitian will challenge the eating disorder voice in your head and work with you to increase your calorie intake (goal number one) and challenge the fears you have around eating and/or specific foods (goal number two). 

If you’re an adolescent, a dietitian will look at your growth charts and determine a minimum weight that would likely be appropriate for you. This is called “biologically appropriate weight.” It isn’t an exact science, and it’s important for parents to understand that it’s OK for their children to go above these minimum weight goals. A good eating disorder dietitian will never tell you that you should stop gaining weight after a certain point. It’s impossible to predict exactly where your body weight will end up when you’re in recovery.

A dietitian will also create some kind of eating plan for your anorexia nervosa treatment. The exact type plan will vary based on the person and the circumstances. It’s not uncommon that patients with anorexia nervosa will need to eat around 5,000 calories per day in order to gain weight at an appropriate speed (at least 1 pound per week). This is because anorexia nervosa can make people hypermetabolic — meaning their metabolism burns through calories very quickly.

How do dietitians come up with meal plans for anorexia nervosa recovery?

Plate of burger and fries on wood table. An anorexia nervosa recovery meal plan gives you plenty of calories for weight regain and health.

Different dietitians take different approaches to meal plans for recovery. I love the Plate-by-Plate Approach®, which is designed to help parents feed their child with an eating disorder. It doesn’t use numbers or measuring. Instead, it teaches you what a recovery plate should look like, and which foods should be eaten at each meal and snack in which (approximate) amounts.

Some dietitians use an exchange system, assigning patients a certain number of “exchanges” of various foods per day. Each exchange is a set serving size of a certain food group, like starchy carbs, protein, dairy, fat, fruits, and vegetables. Someone on an exchange system might be assigned 4 carb exchanges, 2 protein exchanges, 1 fat exchange, 1 dairy exchange, 1 fruit exchange, and 1 vegetable exchange per meal. The exchange system is used in most inpatient treatment centers as well.

Further along in recovery, dietitians also help patients overcome fear of various foods, and of eating in general. We typically do this through food exposures. We’ll identify a food that you’re afraid to eat, and help you come up with a plan to eat it in a comfortable setting with people you trust. The first time, it’s really hard and uncomfortable. The second time it’s a little easier. And every time after that keeps getting easier and easier, until it’s not something you worry about anymore.

A dietitian also serves as a counselor in the anorexia recovery process. We play a different role than mental health therapists, but we still talk with patients (and their parents) about their struggles with food and body image, their fears around food and eating, and what motivates them to recover. We also help patients practice techniques to help them get through difficult moments and hard eating experiences without going back to eating disorder behaviors.

How do you find a dietitian to help you with recovery?

If you’re struggling with an eating disorder, finding the right providers is so important. But it can be hard! Look for a dietitian who specializes in eating disorders and takes a Health at Every Size® approach. Then, schedule a time to talk with them and see if you get along. 

(To learn more about our nutrition counseling services for eating disorders and book a free consult, go here. We offer counseling in-person in Raleigh, North Carolina, and virtually across North Carolina and in several other states.) 

Depending on how severe your eating disorder is and what your life looks like, you might need inpatient treatment. Two eating disorder treatment centers I love are Monte Nido & Affiliates and the Eating Recovery Center. Both have treatment centers across the country. If your outpatient (AKA private practice, someone you see once or twice a week) dietitian or therapist recommends inpatient treatment, they might refer you to one of these treatment centers. If you don’t have outpatient providers and want to refer yourself, you can reach out to the intake team at these treatment centers.

Bottom line: Anorexia nervosa is a serious disease that deserves high-quality care.

If you’re struggling with anorexia (or any eating disorder!), reach out as soon as possible. The sooner you begin treatment, the more likely you are to recover.

If you’re struggling with an eating disorder or disordered eating, we can help! We’re a group of dietitians who takes an anti-diet, body-positive, identity-affirming approach to recovery and healing your relationship with food. . Learn more about nutrition counseling, offered in Raleigh, NC, and virtually to clients in several states. Not ready to commit to counseling but want more information about the anti-diet approach? Subscribe to our weekly newsletter.

You might also like:

What Is Orthorexia — And Do I Have It?

What Is Bulimia Nervosa? How Can A Dietitian Help?

What Is Intuitive Eating? Why Is it Better Than Dieting?

18 Dietitian-Recommended Snacks for Eating Disorder Recovery

Free Intuitive Eating Course

Looking for a free intuitive eating course? Whether you’re new to the anti-diet approach or you’ve been trying to work towards intuitive eating for a while, our 5-Day Intuitive Eating Starter Course is a great start for anyone who’s tired of obsessing over “wellness” and constantly struggling with food and body acceptance.


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