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People with anorexia nervosa commonly experience profound distortions in how they view their own bodies. They often see themselves looking in the mirror as fat, even though they are emaciated.

Every aspect of their lives is colored by their constant obsessions about weight, food, and body image. Such obsessive thoughts and perceptual disturbances result from the malfunctioning of a starving brain.

Neurotransmitters and Conventional Medication

To improve anorexic patients’ mood and behavior, conventional psychiatrists prescribe medications. These affect levels of neurotransmitters in the brain in different ways.

While hundreds of neurotransmitters have been identified thus far by science, there are three in particular that have been studied extensively and found to strongly influence emotion and behavior: serotonin, dopamine, and norepinephrine.

All three of these neurotransmitters are constructed from amino acid precursors obtained from the diet. The precursor for serotonin is tryptophan, while the precursors for dopamine and norepinephrine can be the amino acids phenylalanine or tyrosine.

The chemical pathway from amino acid precursor to neurotransmitter is complicated and requires vitamins such as folic acid, B6, and B12, as well as minerals such as zinc, magnesium, copper, and iron.

Most neurotransmitters are under precursor control, which means that not eating specific amino acids will result in depleted amounts of the related neurotransmitters in the brain. This can help explain why, in general, psychiatric medications have consistently proven to be ineffective for treating anorexia nervosa.

Medications that work by regulating certain neurotransmitters won’t accomplish very much if levels of those target neurotransmitters are deficient! Psychiatric medication inefficacy is likely the result of inadequate amounts of available amino acid precursors to make neurotransmitters.

If you don’t have enough protein, you can’t make neurotransmitters.

Medications that work by increasing neurotransmitter levels are ineffective when you can’t produce neurotransmitters in the first place.

Essential Amino Acids

When talking about protein and diet, it’s important to remember that your body does not use “whole” protein molecules. Your digestive system breaks down proteins from food into their individual amino acids.

Then, using the blueprints from your own DNA, your body reassembles them into more than 50,000 different structural and functional proteins.

Of the twenty-one amino acids, there are nine we cannot make within our bodies and which, accordingly, we must obtain through the foods we eat or via supplements. They are “essential”—because it’s essential we get them in our diet.

Whenever the body needs new proteins, enzymes combine individual amino acids, linking them together to create new proteins. Proteins can have thousands of amino acids bonded together in specific sequences.

Imagine a huge, ever-changing three-dimensional jigsaw puzzle that is constantly being put together and taken apart, depending on the variable needs of your body. While most people consider the importance of amino acids for maintaining metabolic and physical health, amino acids are often overlooked insofar as the roles they play in supporting mental health.

They are precursors to the “biochemical keystones” of cognition, mood, and brain function: neurotransmitters.

Amino Acids and Mental Health

People with anorexia restrict their food intake and, in so doing, frequently stop eating protein. This can lead to an amino acid deficiency. But people with anorexia can become deficient in amino acids in another way, too.

Even if they do eat protein, their bodies may be so damaged from long-term self-starvation that they can’t produce adequate amounts of digestive enzymes. Low digestive enzyme levels cause the digestive cascade to function poorly, and foods aren’t sufficiently broken down as a result. And when proteins aren’t broken down, they cannot be absorbed in the gastrointestinal tract to be used by the body.

When individuals with anorexia drastically reduce protein intake, the little protein that they do eat is used only for the most vital bodily processes. Nonessential biological functions, on the other hand, begin to be shut down by the body itself.

Hormone production slows, causing menstruation to stop. Muscle wasting, thinning skin, and susceptibility to infections are common. Cuts and bruises can take longer to heal, and hair and nails can become brittle, breaking easily.

Eventually, even essential functions, including those that regulate the activity of the heart, become altered. Heart abnormalities are frequently observed in people with severe anorexia nervosa.1

Normal Weight Does Not Guarantee Normal Amino Acid Levels

A study conducted in Germany measured levels of various amino acids in three groups of people: acutely underweight anorexia patients, weight-recovered outpatients, and healthy women.2

Results from a single blood sample showed that both the weight-recovered and acutely ill subjects with anorexia had significantly lower levels of tryptophan and phenylalanine than did the healthy control subjects.

The study researchers concluded that normal-weight alone did not signify healthy eating habits or normal amino acid levels, even though the weight-recovered individuals had a normal BMI, regained menstruation, and had not binged, purged, or engaged in restrictive behaviors for at least three months.2

These weight-recovered individuals were almost certainly eating diets that were nutrient-deficient, and their blood testing showed that their amino acid status was abnormal.

In the second part of the same study, underweight patients with anorexia were followed as they partook in a highly structured inpatient treatment program, which included careful monitoring of the patients’ dietary protein intake. At the end of this program, the patients had gained weight, and their amino acid levels were not significantly different from those of healthy controls.2

This study emphatically supports what I see every day in my practice: the focus on weight restoration without careful monitoring of nutritional repletion leaves patients vulnerable to chronic nutritional deficiencies.

It’s not the weight, it’s the nutrition. If you get the nutrition right, the weight takes care of itself.

Amino Acid Supplementation

Simply urging an individual with anorexia to eat meat, however, will not solve the problem. Yet the brain cannot function optimally—or even normally—without an adequate supply of amino acids.

Adding large amounts of protein to the diet without digestive enzymes and hydrochloric acid often creates increased physical discomfort in patients with anorexia, including bloating, diarrhea, and constipation.

For this reason, until patients are eating adequately and capable of digesting protein properly and efficiently, amino acid supplements and digestive enzymes should be taken to support nutritional recovery and minimize gastrointestinal discomfort.

For individuals who have struggled for many years, free-form amino acids are pivotal for recovery. As single molecules, free-form amino acids are not attached by peptide bonds to other amino acids to form chains, so they do not need to be digested.

They can be absorbed easily and directly into the body, ready to help rebuild tissues, make hormones, synthesize neurotransmitters, and reverse physical deterioration.


I recommend that free-form amino acids be taken twice daily: thirty minutes before breakfast, and then again thirty minutes before dinner. This may come either in capsule or powder form. In my career to date, I have never observed any side effects from amino acid supplements taken in the form of free-form powders.

For anorexia patients suffering from depression and chronic fatigue, amino acid supplementation can be especially life-changing. Free-form amino acids have the power to improve mental clarity, elevate mood, help the body effectively cope with stress, and enhance sleep quality.

I have found that free-form amino acids can be the most important supplement that people with anorexia can take to improve mood, address distorted thinking, and decrease anxiety. Amino acid supplements can improve mood, decrease distorted thinking, and relieve anxiety in patients with anorexia. Amino acid blends will simply augment the body’s own ability to rebuild and restore health!

If you’re ready to learn more about using nutritional interventions like these with your patients, please consider enrolling in our comprehensive Fellowship program. This unique training provides 300+ hours of online curriculum in nutritional, functional and precision psychiatry to address the root causes of mental illness. You’ll gain practical protocols you can use immediately in practice to make a lasting difference with your patients.

Ready to learn more about nutritional and functional medicine for mental illness? Enroll in our popular Fellowship program! Book a private phone call today with Dr. James Greenblatt to learn more.

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  1. Giovinazzo S, Sukkar SG, Rosa GM, et al. Anorexia nervosa and heart disease: a systematic review. Eat Weight Disord. 2019;24(2):199‐207.
  2. Ehrlich S, Franke L, Schneider N et al. Aromatic amino acids in weight-recovered females with anorexia nervosa. Int J Eat Disord. 2009;42(2):166-172.