How Can Eating Disorders Affect The Thyroid?

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Eating disorders harm our health and wellbeing in multiple ways.

They don’t allow the body to get the much-needed nutrients it needs for proper functioning.

Since we depend on the nutrients we consume, eating disorders can wreak havoc on multiple organs and glands, thus paving the way to various health problems.

Do eating disorders harm the thyroid? What happens to this gland in the presence of an eating disorder?

What is an eating disorder?

Eating disorders are defined as a persistent disturbance of eating behavior or behavior intended to control weight, which significantly impairs physical health and psychological functioning. In other words, eating disorders fall into the category of psychological conditions wherein a person is pre-occupied with food, body weight, and body shape.

Unhealthy eating behaviors include restriction of dietary intake, overeating with a sense of loss of control, the compensatory behaviors (vomiting, exercise, laxative abuse). Cognitive disturbances, emotional triggers and consequences, and social isolation often accompany unhealthy eating behaviors[i]. More precisely, eating disorders are complex and affect multiple aspects of a person’s life.

The exact cause of eating disorders is unknown. As with other mental health problems, there could be various causes that fall into these categories:

  • Genetics and biology – some people may have a genetic predisposition to develop eating disorders. On the other hand, biological factors include changes in brain chemicals.
  • Emotional and psychological health – it’s not uncommon for people with eating disorders to have emotional and psychological problems that contribute to their disorder. Some of these problems include low self-esteem, troubled relationships, negative body image, impulsive behavior, perfectionism, just to name a few.

While teenage girls and young women are most likely to develop eating disorders, men can develop them as well. Eating disorders can develop at any age but are most likely to occur in the teen years and early 20s. Frequent dieting, especially following fad diets, is also a risk factor for developing an eating disorder. These diets encourage people to severely limit their calorie intake and omit the consumption of certain foods. They lead to starvation, which also happens to be one of the biggest signs of eating disorders as well.

Types of eating disorders

Eating disorder is a broad term that includes many unhealthy eating behaviors. However, the most common eating disorders are:

  • Anorexia nervosa – the most well-known eating disorder. People with anorexia tend to consider themselves overweight even if they are dangerously underweight. They may severely limit their food intake or compensate for it through various purging behaviors. Intense fear of gaining weight is one of the most common characteristics of people with anorexia nervosa
  • Bulimia nervosa – also a well-known eating disorder, indicated by consumption of large amounts of food in a short time frame followed by purging (in the form of vomiting). Just like with anorexia, people who have bulimia are afraid of gaining weight.
  • Binge eating disorder – one of the most common eating disorders, especially in the US. People with binge eating disorder tend to consume large amounts of food in short periods of time, but they don’t purge

Eating disorders and thyroid

Eating disorders have a major impact on the body, and its functions and their consequences also extend to the thyroid gland. That said, studies on this subject do point to the harmful impact on the thyroid gland, but further research is still necessary to uncover all the mechanisms involved.

Studies confirm that abnormal thyroid function in patients with eating disorders stems from malnutrition. In starvation states, low serum T3 levels are common. The reduction in T3 results from decreased peripheral conversion of T4 to T3. Reduced T4 levels are also observed in starvation states[ii]. In other words, starvation states (usually brought on by anorexia) can contribute to hypothyroidism. When the source of energy, which mainly comes from food, is limited, the body strives to tackle this new situation by slowing down.

A study from the Endocrine Practice evaluated the impact of anorexia on endocrine glands. Findings showed that anorexia nervosa is a devastating disease with a variety of endocrine manifestations. The impact of starvation is extensive and affects the thyroid gland, pituitary gland, adrenal glands, gonads, and bones. The same study revealed that persons with anorexia nervosa often exhibit clinical signs of hypothyroidism such as bradycardia (slower heart rate), hypothermia, hypotension, dry skin, and decreased metabolic rate. Biochemically speaking, anorexic patients experience a constellation of thyroid hormone abnormalities quite similar to sick euthyroid syndrome with significantly low T3 and low-to-normal T4 due to reduced peripheral conversion.

Impaired thyroid hormone levels in people with anorexia are multifactorial, with a strong emphasis on the decreased peripheral conversion. Why is that so important? Well, the presence of carbohydrates is important in stimulating the peripheral conversion of T4 to active T3. In anorexia, the consumption of food is severely limited, thus reducing the presence of carbohydrates that are necessary for this process. Moreover, the hypothalamic release of TRH (thyrotropin-releasing hormone) could be impaired in anorexia. The impaired TRH prevents the typically robust TSH (thyroid-stimulating hormone) response to low peripheral thyroid hormone concentration[iii].

Other studies have also demonstrated that patients with anorexia had significantly lower values of serum T3, T4, fT3, fT4, and T3-T4 ratio. Scientists explain that the changes in thyroid hormone levels in anorexia nervosa (and severe depression) are mainly due to impaired conversion of T4 to T3 by elevated cortisol levels in times of emotional stress[iv]. This is particularly important if we bear in mind that anorexia is often accompanied by other mental health problems such as severe stress, anxiety, and depression.

Additionally, a study from the International Journal of Eating Disorders found that malnutrition in people with anorexia can reduce the thyroid volume. Subjects with anorexia had a markedly reduced volume of the butterfly-shaped gland compared to the control group and with the volume expected from age and body weight. These findings indicate thyroid atrophy, which could be involved in a vicious cycle revolving around maintaining anorectic and depressive symptomatology[v].

Could thyroid problems worsen eating disorders?

The relationship between eating disorders and thyroid function is complex and requires more research. While we know that eating disorders such as anorexia can disrupt the functioning of the thyroid gland, the impact of thyroid illnesses on these conditions is still unknown.

A case study from the Journal of Clinical Research in Pediatric Endocrinology reported the comorbid presence of Hashimoto’s thyroiditis and eating disorder anorexia nervosa in a 15-year-old teenage boy. Hashimoto’s thyroiditis is an autoimmune condition and the most common cause of hypothyroidism. Scientists explained that hypothyroidism caused by Hashimoto’s thyroiditis could complicate the management of anorexia nervosa by elevating the susceptibility to gain weight, thus making a patient eat less. Interestingly, the same study reports that Hashimoto’s thyroiditis could disrupt the management of anorexia by causing hyperthyroidism. Although Hashimoto’s usually leads to hypothyroidism, patients may also go through a hyperthyroid phase called hashitoxicosis as thyroid hormone leaks out of the damaged gland as it is destroyed, and eventually, a patient becomes hypothyroid.

Not only did Hashimoto’s thyroiditis complicate the management of anorexia, but vice versa also applied. Anorexia can impair the management of this thyroid condition by altering body weight and the metabolic rate. Moreover, anorexia can also cause drug non-compliance[vi]. These findings show that the relationship between thyroid problems and eating disorders could be a two-way street.

A study from the Eating Behaviors explored the link between thyroid disease and eating disorders. Female, obese patients with and without thyroid disease, were a part of this research. Results showed that the Eating Disorder Examination score was higher in women with current or previous hypothyroidism than in their counterparts. While hypothyroidism was associated with increased shape concerns, this didn’t appear to be related to differences in current levels of thyroid hormones[vii].

Can thyroid function improve in persons with eating disorders?

The impact of eating disorders on the thyroid gland is truly significant. Starvation states impair hormone production and conversion. Metabolism slows down, and symptoms of hypothyroidism may appear. Since the thyroid gland is vital for our overall health and wellbeing, it’s crucial to be proactive about it.

If you, or someone you know, have an eating disorder, it’s important to manage this condition properly. The treatment of an eating disorder depends on the particular type of unhealthy eating behavior and symptoms you experience. In most cases, the treatment includes a combination of therapy, nutrition education, and medical monitoring. Medications are also prescribed in some cases.

When it comes to eating disorders such as anorexia, the biochemical thyroid abnormalities generally correct with proper nutrition and weight gain.

Management of eating disorders requires strong willpower, but it’s possible. For people with thyroid problems, treating the eating disorder can be particularly stressful. The reason is simple, thyroid diseases with an emphasis on hypothyroidism can cause weight fluctuations. Many people tend to gain weight when they’re hypothyroid, and that’s exactly what a person with an eating disorder tries to avoid. A strong urge to avoid weight gain may force a patient to further limit the consumption of food. This creates a vicious cycle where thyroid problem aggravates, and health is severely impaired.

The treatment approach described above can help tackle the eating disorder in a healthy way. Nutrition education and therapy can help a patient adopt a healthier perspective and tackle their fear of weight gain more successfully. Paired with this, it’s important to never get too hungry. Make sure you never get to the point when you’re so hungry that your hands start shaking.

Of course, it’s not all about eating per se, but the foods you eat. Instead of unhealthy foods such as hamburgers, French fries, pizza, and others, you may want to opt for healthier alternatives. Consumption of fruits, vegetables, fish, healthy fats, whole grains, nuts, and seeds can help supply the body with much-needed nutrients while also maintaining weight in a healthy range. Remember, food (especially carbs) is important for the conversion of T4 into active T3.

Other lifestyle modifications are also important for a person with an eating disorder and thyroid problems. One of those modifications is sufficient sleep. Your body rests and recovers as you sleep. But when you don’t get enough good night’s rest, the levels of stress hormone cortisol increase. As mentioned above, high-stress levels can also disrupt the peripheral conversion of T4 to T3.

Eating disorders in numbers

Statistics demonstrate the true severity of eating disorders. Data shows that[viii]:

  • 9% of the world’s population has eating disorders
  • 9% of the US population (28.8 million people) will have an eating disorder at some point in their life
  • 28% to 74% of the risk of eating disorders is through genetic heritability
  • Eating disorders are among the deadliest psychological illnesses, second only to opioid overdose.
  • 10.200 people die every year due to eating disorders (one death every 52 minutes)
  • 26% of people with eating disorders attempt suicide


Eating disorders are prevalent across the globe. Unhealthy eating behaviors jeopardize a person’s health and wellbeing. They also impair the function and decrease the volume of the thyroid gland. The thyroid function can improve when healthy eating is restored. Management of eating disorders requires a combined approach of therapy, nutritional education, and even medications in some cases. However, it’s possible to recover from this disorder. Keep in mind you will need support from loved ones, but when you stick to the treatment, you’ll succeed. If you don’t have an eating disorder but suspect you (or someone you know) might have it, make sure to schedule an appointment to see the doctor.


[i] National Institute for Health and Care Excellence (UK). (2017) Eating disorders: Recognition and treatment.

[ii] Marshall, Z., & Lippmann, S. (1987). How do eating disorders affect thyroid function?. Postgraduate medicine, 82(7), 110–116.

[iii] Usdan, L. S., Khaodhiar, L., & Apovian, C. M. (2008). The endocrinopathies of anorexia nervosa. Endocrine practice: official journal of the American College of Endocrinology and the American Association of Clinical Endocrinologists, 14(8), 1055–1063.

[iv] Natori, Y., Yamaguchi, N., Koike, S., Aoyama, A., Tsuchibuchi, S., Kojyo, K., & Demura, R. (1994). Rinsho byori. The Japanese journal of clinical pathology, 42(12), 1268–1272.

[v] Støving, R. K., Bennedbaek, F. N., Hegedüs, L., & Hagen, C. (2001). Evidence of diffuse atrophy of the thyroid gland in patients with anorexia nervosa. The International journal of eating disorders, 29(2), 230–235.<230::aid-eat1013>;2-p

[vi] Pehlivantürk Kızılkan, M., Kanbur, N., Akgül, S., & Alikaşifoğlu, A. (2016). An Adolescent Boy with Comorbid Anorexia Nervosa and Hashimoto Thyroiditis. Journal of clinical research in pediatric endocrinology, 8(1), 92–95.

[vii] Mannucci, E., Ricca, V., Filetti, S., Boldrini, M., & Rotella, C. M. (2003). Eating behavior and thyroid disease in female obese patients. Eating behaviors, 4(2), 173–179.

[viii] Eating disorder statistics. National Association of Anorexia Nervosa and Associated Disorders.

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