Anorexia has the highest mortality rate of any mental illness. Learn more about the medical complications of anorexia and how to get help. 

When most people think of Anorexia Nervosa, they likely think of those struggling with distorted body image, long-term food restriction and severe weight loss. 

Key Takeaways 

• Anorexia affects nearly every system in the body, including digestion, metabolism, cardiovascular health, and hormones 

• Many complications—like constipation, hair loss, dizziness and fatigue—are early warning signs 

• Others, such as electrolyte imbalances or low heart rate/heart arrhythmias, can become life-threatening without treatment 

• Symptoms may worsen during recovery before improving 

• Early, comprehensive treatment is essential for reversing many complications 

How Anorexia Affects the Body 

Anorexia impacts just about every organ system in the body from head to toe.  There are prominent neurological symptoms such as dizziness, brain fog, and decreased attention span.  Cardiovascular symptoms include bradycardia (low heart rate), orthostatic heart rate changes which result in changes in heart rate and blood pressure when the person goes from sitting/laying to standing.  Gastrointestinal symptoms are often reported such as early fullness and constipation 

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1) Anemia and Anorexia 

Anemia is a lack of red blood cells (RBCs) in the bloodstream. RBCs house hemoglobin, a protein that enables RBCs to carry oxygen from the lungs throughout the body, in addition to transporting carbon dioxide back to the lungs to be exhaled. The body requires folic acid, Vitamin B12 and iron (among other things) to produce healthy and mature RBCs.  

A lack of these nutrients, commonly experienced by someone who is restricting food intake, often leads to anemia and inadequate oxygen transport throughout the body. It could also result in fatigue, weakness, pale skin, irregular heartbeat, shortness of breath, dizziness, chest pain and/or headaches. 

2) Digestive Complications of Anorexia 

Anorexia and Constipation 

Constipation generally involves either having difficulty with or the inability to make a bowel movement for an extended period of time. In some cases on constipation, medical interventions may be necessary. 

People struggling with anorexia more frequently deal with constipation because of inadequate food and fluid intake that can cause decreased gastric motility (ability to move freely). This means that the intestines struggle to properly push food through the digestive system and produce a bowel movement. Those experiencing constipation likely feel an uncomfortable bloat or feeling of extreme fullness.

Healthcare professionals can assess and make recommendations about how to treat the constipation and nutritional rehabilitation is often primary to the treatment.   

Anorexia and Gastroparesis 

Gastroparesis is a condition in which the stomach empties more slowly than normal. In anorexia, this can occur when prolonged restriction affects the muscles and nerves responsible for digestion. As a result, food remains in the stomach longer than expected, leading to discomfort.  During the digestive process material will move more slowly through the entire GI system which also contributes to the feeling of constipation and fullness.   

Common symptoms may include: 

• Early fullness after eating 

• Bloating or abdominal discomfort 

• Nausea 

• Reduced appetite 

Gastroparesis can make it more difficult to meet nutritional needs, especially in recovery. However, this condition is often temporary and can improve with consistent nourishment and medical support. As the body receives adequate energy, digestive function may gradually return to a more typical pattern. 

General Gastrointestinal complaints 

Various GI symptoms are common in patients with anorexia.  Restriction can alter gut motility and sensitivity, leading to: 

• Constipation or diarrhea 

• Abdominal discomfort 

• Gas or bloating 

These symptoms can be confusing and may reinforce avoidance of food. It is important to recognize that digestive discomfort in anorexia is often related to the body adjusting to inadequate intake. With consistent nourishment and support, many of these symptoms improve over time. 

3) Dehydration and Electrolyte Imbalances 

Anorexia and Dehydration 

Most people might think of dehydration as not taking in enough water, or more specifically, when someone loses more water (through urination, defecation, sweating, vomiting, etc.) than they ingest. While this is true, a large percentage of dietary water also comes from solid foods. When someone restricts their food intake, they become more susceptible to dehydration. 

Dehydration can manifest in a number of symptoms including thirst, dark-colored urine, infrequent urination, fatigue, dizziness and confusion. In more serious cases, it can cause a number of secondary complications, such as kidney failure, hypovolemic (low blood volume) shock, electrolyte imbalances and orthostatic hypotension. Treatment of mild dehydration generally begins with adding oral fluids and fortifying the patient’s diet while intravenous (IV) fluid is required in more severe cases. 

Anorexia and Electrolyte Imbalances 

Electrolyte imbalances, which are closely linked to dehydration, also commonly result from restricted diets. Electrolytes such as sodium, potassium, calcium and chloride are essential for the body to function properly. If those electrolytes are not sufficiently represented in one’s diet (as is often the case with AN), the levels will dip and the body’s delicate balance will be thrown off. 

Some electrolyte imbalances seen in anorexia are hyponatremia (a low concentration of sodium ions in the bloodstream) and hypokalemia (a low concentration of potassium ions). A shortage of sodium in the body can impact brain function, causing nausea and vomiting, confusion, headache, fatigue, irritability, muscle weakness or cramps and seizures. 

Hypokalemia can impair muscle (especially heart) function, causing muscle weakness and cramping, an irregular heartbeat, abdominal cramping or bloating, thirst and frequent urination.  

Hypophosphatemia (low phosphorous levels) are also commonly seen and can put patients at higher risk of refeeding syndrome which can be a dangerous shift in electrolytes for patients who are in the early stages of the renourishment process.   

4) Metabolic Changes in Anorexia 

Anorexia and Hypermetabolism 

Hypermetabolism can occur during eating disorder recovery when the body requires more energy than expected. After a period of restriction, the body begins to repair tissues, restore organ function, and rebuild energy stores. This process can temporarily increase metabolic rate. 

As a result, individuals may experience: 

• Increased hunger 

• Difficulty maintaining weight 

• Higher energy needs 

While this can feel unexpected, hypermetabolism is a normal biological response to recovery. It reflects the body working to heal and restore balance. Consistent nourishment is essential during this phase to support physical recovery and prevent setbacks. Over time, metabolic needs typically stabilize as the body returns to a more regulated state. 

5) Orthostatic Hypotension and Anorexia 

Another complication of anorexia is orthostatic hypotension (OH), which is a drop in blood pressure when getting up from a laying to sitting position or from a sitting to a standing position. 

Orthostatic hypotension is common in people suffering from anorexia because inadequate food and fluid intake can lead to dehydration which in turn, can cause low blood pressure. If someone is not taking in enough liquids, their overall fluid volume can decrease, resulting in a blood pressure insufficient to push blood to all parts of the body (most notably the brain). 

Additionally the heart muscle is weaker and less efficient in patients with anorexia.  When blood pressure drops too much or too rapidly, the patient can experience dizziness or lightheadedness, blurry vision, weakness, confusion, nausea or fainting. Treatment generally includes addressing the underlying cause (usually dehydration in cases of anorexia), mostly with oral or IV fluids. 

6) Physical Changes in Anorexia 

Anorexia and Hair Changes 

Hair changes are a common physical effect of anorexia and often reflect how the body responds to inadequate nutrition. When the body does not receive enough energy, it prioritizes essential functions and reduces resources for hair growth. 

This can lead to: 

• Hair thinning or shedding 

• Dry or brittle texture 

• Slower growth 

At the same time, some individuals may develop lanugo, a fine body hair that helps retain heat. These changes can feel distressing, but they are often reversible with consistent nourishment and medical support. 

As the body begins to recover and receive adequate nutrients, hair growth typically improves over time. 

Pale Skin and Easy Bruising 

Patients with anorexia often have lower numbers of blood cells when in the malnourished state. This can result in a pale appearance to the skin.  Additionally patients often report easy bruising which can be due to decreased subcutaneous tissue which normally protects underlying blood vessels.  

7) Appetite and Hunger Changes 

Anorexia and Loss of Appetite 

Loss of appetite is common in anorexia and may seem confusing. Despite not eating enough, individuals may feel little or no hunger. This occurs because the body adapts to prolonged restriction by suppressing hunger signals. 

Contributing factors may include: 

• Hormonal changes 

• Slowed metabolism 

• Psychological factors related to food 

Even without hunger cues, the body still requires nourishment. Relying on appetite alone can delay recovery. Structured eating and consistent support help restore hunger signals over time. 

As the body begins to receive adequate nutrition, appetite often becomes more reliable. 

Anorexia and Extreme Hunger 

Extreme hunger can occur during recovery as the body works to restore energy balance. After a period of restriction, the body increases hunger signals to meet its needs for repair and stabilization. 

This may include: 

• Frequent or intense hunger 

• Thinking about food often 

• Larger portions than expected 

While this can feel overwhelming, it is a normal response to energy deprivation. It does not mean something is wrong. 

Responding to hunger with consistent nourishment supports recovery and helps the body move toward balance. Over time, hunger signals typically become more stable and predictable. 

When Anorexia Complications Require Immediate Care 

Some symptoms of anorexia require urgent medical attention. These may indicate serious complications that need immediate evaluation. 

Seek care if you or someone else experiences: 

• Fainting or loss of consciousness 

• Chest pain 

• Severe dehydration 

• Confusion or difficulty thinking clearly 

• Persistent vomiting 

• Rapid or irregular heart rate 

If these symptoms are present, it is important to seek medical care as soon as possible. 

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FAQs About Anorexia Complications 

What are the most common complications of anorexia? 

Common complications include digestive issues, fatigue, hair loss, dehydration, and hormonal changes. 

Can anorexia cause permanent damage? 

Some complications can become long term if not treated early, but many improve with proper care and recovery. 

Are digestive issues common in anorexia? 

Yes. Conditions like constipation, bloating, and delayed gastric emptying are frequently reported. 

Why do symptoms sometimes worsen during recovery? 

As the body begins to heal, systems such as digestion and metabolism adjust, which can temporarily increase discomfort. 

When should someone seek medical help? 

Medical help should be sought when symptoms affect daily functioning, worsen over time, or include serious physical signs such as dizziness or fainting. 

Reach Out for Help with Anorexia Nervosa Complications 

The medical complications and risk around anorexia don’t stop with these five areas. Others may include low heart rate, osteoporosis, kidney failure, stunted physical growth and more. 

If you – or someone close to you – is suffering from anorexia or experiencing any of the symptoms in this blog, don’t be afraid to reach out for help. 

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