Anyone can experience a loss of appetite for many different reasons. These include medical conditions, mental health conditions, and medication side effects.

Alongside a loss of appetite, a person may also experience fatigue and weight loss if they are not eating enough food to sustain their body.

In this article, we examine what causes a loss of appetite, what it means, its complications, and how to treat it.

Hunger is a physiological need for food, driven by the body’s energy requirements. Appetite is the desire to eat, and certain factors, such as emotions, habits, or sensory appeal, help influence it.

A loss of appetite is often temporary due to factors such as infections or digestive issues. A person’s appetite typically returns when they have recovered.

Some people may also lose their appetite as a symptom of a long-term medical condition, such as in the late stages of a serious illness, including cancer. This is part of a condition that doctors call cachexia.

The medical term for a complete loss of appetite over a more extended time is anorexia. This is different from the eating disorder anorexia nervosa, which is a mental health issue.

Below, we look at the possible causes of appetite loss.

Common causes

Common viral or bacterial infections, such as flu or gastroenteritis, are often responsible for appetite loss. A person’s appetite usually returns when they start to recover.

Common short-term causes of feeling a loss of appetite include:

People experiencing issues that cause mouth pain, such as sores, may also experience a loss of appetite if it becomes difficult to eat.

Medical conditions

Long-term medical conditions can cause a loss of appetite for a range of reasons that vary depending on the cause. Loss of appetite can have links to lowered immune system function, feeling unwell, and having an upset stomach.

Medical conditions that can cause a loss of appetite include:

Side effects of medications

A loss of appetite is a common side effect of many medications, along with other digestive issues, such as constipation or diarrhea. This is common when medications pass through a person’s stomach and digestive tract.

Medications and treatments that often cause a loss of appetite include:

If people have recently undergone major surgery, they may experience a loss of appetite after the operation. This feeling can have partial links to anesthesia drugs.

Using drugs recreationally, such as cocaine, cannabis, and amphetamines, can also cause a loss of appetite.

Psychological causes

Psychological factors and mental health conditions can significantly affect a person’s appetite. These can include:

Age

A loss of appetite can also be more common in older adults. This can be due to increased use of medications and changes in the body as it ages. These changes can affect:

  • the digestive system
  • the hormones
  • the sense of taste or smell

Some cancers

A loss of appetite or unexpected weight loss can sometimes be a symptom of certain cancers, such as pancreatic, ovarian, or stomach cancer.

Alongside a loss of appetite, people may experience the following symptoms:

  • stomach pains
  • heartburn
  • feeling full quickly
  • yellowing of the skin, eyes, or both
  • blood in the stool

If people experience any of these symptoms, they need to consult a doctor who will be able to find out the underlying cause.

People with serious medical conditions may experience a loss of appetite, which can be due to the illness itself or as a side effect of treatments, such as chemotherapy for cancer.

Some individuals in the later stages of serious illnesses may experience cachexia. This is the term for weight loss, muscle wastage, and general ill-health due to chronic, life-limiting illnesses.

Those with cachexia can get nutritional advice from their doctor, who can help create a nutritional plan to help ensure they get the necessary calories and nutrients.

A person with a serious illness needs to speak with a doctor if they have a complete loss of appetite for a day or more or any of the following:

  • vomiting for a day or longer
  • an inability to keep liquids down
  • pain when trying to eat
  • irregular urination

A doctor may prescribe certain medications to help increase appetite and reduce other symptoms, for example, nausea.

If depression or anxiety are causing people to experience a loss of appetite, talking therapies and sometimes antidepressants can help.

If a doctor suspects that a specific medication is causing a loss of appetite, they may be able to change the dosage or the medication.

People may find it easier to eat several smaller meals per day instead of three bigger ones.

A person can aim to make these meals high in nutritional value to ensure the body is getting plenty of protein, micronutrients, and energy. They may also find having liquid meals, such as smoothies and protein drinks, easier to take.

Adding herbs, spices, or other flavorings to meals may also encourage people to eat more easily. Eating meals in relaxing or social settings may make eating more enjoyable.

People can also keep drinking plenty of fluids to prevent dehydration. Gentle exercise, such as a short walk, may sometimes increase appetite as well.

A doctor will look at all the symptoms a person is experiencing and use these to work out the possible cause of their loss of appetite.

A doctor may examine a person’s abdomen by feeling with their hand for any atypical bloating, lumps, or tenderness. This can help them determine if a gastrointestinal disorder is causing a loss of appetite.

A doctor may also carry out tests to help them work out the cause. Tests can include:

  • blood tests
  • an abdominal X-ray
  • an endoscopy, where a camera enables doctors to look inside the body

A continued loss of appetite can cause weight loss and malnutrition. It is vital for people to discover the reason for their appetite loss, as leaving it untreated can be serious.

People can talk with a doctor if they experience a loss of appetite for a prolonged period. If they notice any unexpected or rapid weight loss, they also need to seek medical attention.

An individual needs medical help if they notice any other symptoms alongside a loss of appetite, such as:

  • stomach pain
  • fever
  • shortness of breath
  • coughing
  • a rapid or irregular heartbeat

People can experience a loss of appetite for a wide range of reasons. Some are short term, including colds, food poisoning, other infections, or the side effects of medication. Others relate to long-term medical conditions, such as diabetes, cancer, or life-limiting illnesses.

Appetite loss often comes with feelings of fatigue or nausea. If a person has concerns about a loss of appetite, they need to tell their doctor and discuss their symptoms.

Treatments for appetite loss will depend on the cause. People may benefit from eating small, regular meals instead of three large meals, and liquid meals are often more palatable.