The medical profession and the general public alike have long misunderstood eating disorders. Often previously thought to be a reactive disorder driven by cultural pressures alone, increasing research indicates that biological factors play an essential role in these highly impactful diseases.
In reality, the science behind eating disorders is complex. They involve a combination of cultural, family, psychiatric, and biological factors. Understanding these influences is important for gaining a holistic view of the causes and potential treatment options for eating disorders.
Eating disorders can be incredibly harmful with potentially lethal complications. If you are worried that you or a loved one may have an eating disorder, seek support from your healthcare provider. This information is not intended to replace professional medical advice.

What are eating disorders?
The DSM-5 is a diagnostic manual used by clinicians to classify mental health conditions. It recognizes several distinct eating disorders, including: [1]
- Anorexia Nervosa – features a restriction of energy intake that leads to a significantly low body weight. Anorexia nervosa is characterized by an intense fear of weight gain and a distorted body image, either with or without purging.
- Bulimia Nervosa – includes recurrent binge eating episodes, which are followed by recurrent compensatory behavior (such as forced vomiting or excessive exercise).
- Binge Eating Disorder – characterized by recurrent episodes of uncontrollable eating binges, leading to feelings of discomfort or guilt.
Are Eating Disorders Genetic?
Genetic factors form one of the key biological contributors to anorexia nervosa and other eating disorders. Although the presence of specific genes does not guarantee the emergence of an eating disorder, it can substantially increase the risk.
Twin studies and eating disorders
One of the main reasons we know that there are biological factors of eating disorders is from observing twins. Researchers commonly use twin studies to differentiate between conditions driven by genetic inheritance and those driven by a shared family environment.
Identical twins share 100% of their genes, whereas fraternal twins only share around 50%. As each set of twins is exposed to the same family and environmental factors, any increased risk of a condition amongst identical twins, when compared to fraternal twins, must be genetic. [2]
Genetic predispositions have been noted for the disorders of anorexia and bulimia nervosa. Genetic factors may also underlie the presence of symptoms, such as binge eating, self-induced vomiting, and dietary restriction. [2]
Specific gene variants in eating disorders
One 2019 study identified eight distinct gene variants linked to anorexia nervosa. Of particular interest, this study suggests that anorexia nervosa shares a similar genetic basis to other mental health conditions, such as depression, anxiety, and obsessive-compulsive disorder (OCD). [3]
In fact, researchers have labeled anorexia nervosa as a metabolic condition and a psychiatric condition (otherwise known as a ‘metabolo-psychiatric’ condition), as it includes features of both.
The Role of the Brain in the Development of Eating Disorders
After making the link to genetics, it’s worth considering the effect these differences can have on brain chemistry and development. Research into the biological causes of eating disorders is still developing, and many theories are still to be fully supported.
The role of serotonin and dopamine in eating disorders
Serotonin is a chemical present in the brain that primarily stimulates the reward pathways and impacts mood. Altered levels of serotonin have long been linked to impulsivity and various mood disorders. Dysregulated serotonin levels have also been correlated with eating disorders. [4]
Serotonin has a significant effect on regulating eating behavior. However, studies are conflicting as to the exact mechanism behind why altered serotonin can lead to dysregulated eating. [4]
A similar uncertain pattern is seen with dopamine. Dopamine also plays a central role in the reward pathways of the brain. Abnormal fluctuations in dopamine levels are thought to contribute to binge eating behaviors, potentially related to perceived rewards in association with food. [5]
Structural changes to the brain in eating disorders
Eating disorders have the potential to lead to significant malnutrition. Many studies have examined the impact of related malnutrition on brain structure. Lack of vital nutrients and minerals can lead to loss of gray and white matter, altering the structure and function of the brain. [6]
However, there is also some evidence that people who are affected by binge eating may already have alterations in their brain’s signaling pathways. These changes may help explain why some people are more vulnerable to developing eating disorders. [7]
Brain plasticity and eating disorders
Brain plasticity refers to the brain’s ability to change its structure and function to adapt to its experiences. Younger people have far greater brain plasticity than fully mature adults.
It is theorized that this increased neuroplasticity may, in part, explain why eating disorders affect such a large number of young people. As the structure and function of the brain changes, it is more susceptible to morph in ways that continue to fuel the symptoms of an eating disorder. [8]
Hormonal Influences on Eating Behavior
Hormones control various functions throughout the body, including appetite and eating behaviors. Disruptions of these hormones’ normal functions can lead to a variety of health conditions. One area of increasing scientific interest is the role hormones play in the development of eating disorders.
Leptin
Leptin is a hormone released by fat tissue that helps regulate appetite, metabolism, and energy regulation. Abnormalities in leptin levels have typically been associated with obesity. [9]
However, dysregulated leptin levels may also contribute to the ongoing cycle of anorexia nervosa and other eating disorders. Deficiencies in leptin following starvation or severe energy restriction may disrupt appetite and discourage sufficient energy intake. [10]
Ghrelin
Ghrelin is a hormone that is similar to leptin. Ghrelin has a central role in stimulating appetite and food intake. People suffering from anorexia nervosa have been found to have consistently elevated levels of ghrelin, as the body is starving and continues to promote food consumption. This demonstrates that, despite strong biological influences trying to regulate food consumption, eating disorders can maintain a powerful hold over individuals’ brain responses. [11]
Cortisol
Cortisol is one of the most widespread hormones in the body, produced in response to physical or psychological stress. As you might expect, people suffering from anorexia nervosa have increased levels of cortisol in the body, resulting from the additional stress applied to the body. [12]
Researchers have identified a number of adverse health consequences associated with high cortisol levels, such as reduced bone density and poor cognitive performance. [12]
What Role Does the Gut Microbiome Play?
The gut microbiome is a complex and fascinating area of emerging research. We are increasingly seeing the significant role gut microbes play in various physical and mental health conditions. The influences of the gut microbiome may provide an important link between the psychiatric and physical components of eating disorders.
Gut-brain axis
Many researchers have dubbed the gut microbiome as a ‘second brain.’ The development of the gut microbiome as we age is similar to brain development, being influenced by genetics, diet, and environmental exposures. [13]
Communication between the brain’s emotional and cognitive centers and the functions of the gastrointestinal tract exists as a two-way system. Disruption of this delicate balance between the brain and the gut is thought to contribute to a variety of conditions, including irritable bowel syndrome (IBS) and eating disorders. [14]
Influence of the gut microbiome on eating disorders
Research has shown that individuals who have eating disorders have a unique microbiome. These changes may occur due to nutritional deficiencies, altered digestive tract functioning, or hormonal axis imbalances. [13]
Alterations in gut microbes can worsen the symptoms of eating disorders, contributing to the common cycle of treatment resistance. [13]
Metabolic Factors of Eating Disorders
Metabolism refers to the chemical reactions that occur throughout the body’s cells that turn food into energy. Eating disorders can have a significant impact on the normal function of an individual’s metabolism. However, baseline differences in metabolism may also contribute to the increased risk of developing an eating disorder.
Metabolic differences
Resting metabolic rates differ between individuals based on many factors, such as diet, physical exercise, activity level, age, sex, genetics, and others. Specifically, research increasingly shows that genetics are crucial in determining an individual’s resting metabolic rate. [15]
The role of metabolic differences in eating disorders
Metabolic abnormalities in anorexia nervosa result from the body’s response to a state of starvation. These changes can introduce significant barriers to weight gain and long-term recovery. [3]
However, recent research indicates that many of these metabolic changes may also have a genetic origin. This further illustrates why some people are more susceptible to developing an eating disorder than others. [3]
What Does This Mean for the Treatment of Eating Disorders?
Understanding the biological factors of eating disorders is vital for identifying the causes and triggers of these conditions. The science behind anorexia nervosa and other related conditions is constantly progressing. Research into this field has also helped identify a variety of potential treatment approaches that aren’t limited to focusing on the psychiatric element of eating disorders alone.
Impact of biological factors on treatment approaches
A wide range of novel treatment approaches have been theorized based on the biological influences of eating disorders:
- Understanding the role that serotonin has in eating disorders allows for the development of more individualized treatment options. Those with serotonin dysregulation may benefit from therapies beyond just nutritional replacement, focusing also on stabilizing brain serotonin. [4]
- Dopamine is an important biomarker that relates to binge eating. Identification of individuals with abnormal dopamine regulation allows for the possibility of earlier identification and treatment of eating disorders. [5]
- Regulation of key hormones, such as leptin and ghrelin, may aid in eating disorder recovery. The medication metreleptin shows promise in its ability to support anorexia recovery. [10] [16]
- Interventions, such as probiotics, microbiome-supplemented foods, and fecal transplants, have the potential to treat disruptions to the gut microbiome seen in eating disorders. [13]
- Inside Out Institute. DSM-5 Diagnostic Criteria for Eating Disorders.; 2013. https://insideoutinstitute.org.au/assets/dsm-5%20criteria.pdf
- Berrettini W. The Genetics of Eating Disorders. Psychiatry (Edgmont). 2004;1(3):18. https://pmc.ncbi.nlm.nih.gov/articles/PMC3010958/
- Watson HJ, Yilmaz Z, Thornton LM, et al. Genome-wide association study identifies eight risk loci and implicates metabo-psychiatric origins for anorexia nervosa. Nature Genetics. 2019;51(8):1207-1214. https://pubmed.ncbi.nlm.nih.gov/31308545/
- Steiger H. Eating disorders and the serotonin connection: state, trait and developmental effects. Journal of Psychiatry and Neuroscience. 2004;29(1):20. https://pmc.ncbi.nlm.nih.gov/articles/PMC305267/
- Yu Y, Miller R, Groth SW. A literature review of dopamine in binge eating. Journal of Eating Disorders. 2022;10(1). https://jeatdisord.biomedcentral.com/articles/10.1186/s40337-022-00531-y
- Scharner S, Stengel A. Alterations of brain structure and functions in anorexia nervosa. Clinical Nutrition Experimental. 2019;28(2352-9393). https://www.sciencedirect.com/science/article/pii/S2352939318300484
- Wang AR, Fiene Marie Kuijper, Barbosa DAN, et al. Human habit neural circuitry may be perturbed in eating disorders. 2023;15(689). https://pubmed.ncbi.nlm.nih.gov/36989377/
- The Brain and Eating Disorders. FREED from ED. https://freedfromed.co.uk/img/guides/The_Brain_And_Eating_Disorders-FREED.pdf
- Kim Y, Hersch J, Bodell LP, et al. The association between leptin and weight maintenance outcome in anorexia nervosa. Int J Eat Disord. 2021;54(4):527-534. https://pmc.ncbi.nlm.nih.gov/articles/PMC9851598/
- Hebebrand J, Moritz Plieger, Milos G, Peters T, Anke Hinney, Antel J. Does hypoleptinemia trigger entrapment in anorexia nervosa? Etiological and clinical considerations. European eating disorders review. 2024;32(3):557-574. https://onlinelibrary.wiley.com/doi/full/10.1002/erv.3071
- Schalla M, Stengel A. The Role of Ghrelin in Anorexia Nervosa. International Journal of Molecular Sciences. 2018;19(7):2117. https://pmc.ncbi.nlm.nih.gov/articles/PMC6073411/
- Luz Neto LM da, Vasconcelos FMN de, Silva JE da, Pinto TCC, Sougey ÉB, Ximenes RCC. Differences in cortisol concentrations in adolescents with eating disorders: a systematic review. Jornal de Pediatria (English Edition). 2019;95(1):18-26. https://www.sciencedirect.com/science/article/pii/S0021755718300767
- Terry SM, Barnett JA, Gibson DL. A critical analysis of eating disorders and the gut microbiome. Journal of Eating Disorders. 2022;10(1). https://jeatdisord.biomedcentral.com/articles/10.1186/s40337-022-00681-z
- Carabotti M, Scirocco A, Maselli MA, Severi C. The gut-brain axis: interactions between enteric microbiota, central and enteric nervous systems. Annals of Gastroenterology : Quarterly Publication of the Hellenic Society of Gastroenterology. 2015;28(2):203. https://pmc.ncbi.nlm.nih.gov/articles/PMC4367209/
- McMurray RG, Soares J, Caspersen CJ, McCurdy T. Examining Variations of Resting Metabolic Rate of Adults. Medicine & Science in Sports & Exercise. 2014;46(7):1352-1358. https://pmc.ncbi.nlm.nih.gov/articles/PMC4535334/
- Milos G, Antel J, Kaufmann LK, et al. Short-term metreleptin treatment of patients with anorexia nervosa: rapid on-set of beneficial cognitive, emotional, and behavioral effects. Translational Psychiatry. 2020;10(1):1-10. https://www.nature.com/articles/s41398-020-00977-1
Our Medical Affairs Team is a dedicated group of medical professionals with diverse and extensive clinical experience who actively contribute to the development of our content, products, and services. They meticulously evaluate and review all medical content before publication to ensure it is medically accurate and aligned with current discussions and research developments in mental health. For more information, visit our Editorial Policy.
MentalHealth.com is a health technology company guiding people towards self-understanding and connection. The platform provides reliable resources, accessible services, and nurturing communities. Its purpose is to educate, support, and empower people in their pursuit of well-being.

Olly is a medical writer with 7+ years of experience in clinical medicine. He holds a Bachelor of Medicine and Surgery and a Bachelor of Medical Science.
Jennie Stanford is a dual-board certified physician in both family medicine and obesity medicine, holding an MD, FAAFP, and DipABOM. She has experience in both clinical practice and peer-quality reviews.
Our Medical Affairs Team is a dedicated group of medical professionals with diverse and extensive clinical experience who actively contribute to the development of our content, products, and services. They meticulously evaluate and review all medical content before publication to ensure it is medically accurate and aligned with current discussions and research developments in mental health. For more information, visit our Editorial Policy.
MentalHealth.com is a health technology company guiding people towards self-understanding and connection. The platform provides reliable resources, accessible services, and nurturing communities. Its purpose is to educate, support, and empower people in their pursuit of well-being.