Can you Throw up from not Eating All-day?

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Is it common for healthy individuals to throw up from not eating all day?

It is extremely rare for healthy people to experience nausea or throw up from fasting all day. Typically, fasting for long hours may induce mild nausea, but not throwing up.

Throwing up from fasting is more likely to occur in people with stomach issues than in those who are completely healthy.

So, fasting for several hours or all day cannot alone explain throwing up. You have to search for other diseases, medications, or psychological causes for such a case.

Although there are no studies targeting this issue specifically, however, the world is full of examples of people who fast all day long without significant stomach issues.

For example, people who follow intermittent fasting for weight loss often fast for several hours or more than a day.

Also, every year, More than a billion Muslims fast in Ramadan for 15 to 20 hours daily. And throwing up is not a recognized symptom of those who fast all day long.

As a gastroenterologist, I learned that anything could happen (including throwing up from not eating). But to our knowledge, it is unlikely to happen in patients with a healthy stomach.

Always search for a cause if you throw up after not eating all day.

What are the possible mechanisms of nausea & vomiting after several hours of fasting?

As we explained before, vomiting is unlikely to occur in a perfectly healthy stomach. So instead, often think of a pre-existing condition that predisposes to vomiting.

The following are the possible mechanisms that may cause vomiting:

A. Acid build-up:

Not eating for several hours or all day long will empty your stomach from any food.

The main digestive fluid secreted by your stomach is HCL (stomach acid). It is a very irritant substance that can irritate your digestive system, especially if you have a pre-existing stomach disease.

For example, people with duodenal ulcers start to experience stomach pain, nausea, and vomiting if they don’t eat for several hours.

The reason behind this phenomenon is the build-up of stomach acid, leading to irritation of the ulcer in the duodenum. Eating will buffer the acidity of the stomach and will relieve the symptoms (reference).

The acid build-up is often not an issue in people with a healthy stomach. However, it may induce throwing up in those with duodenal ulcers, stomach ulcers, and acid reflux after fasting for long hours.

B. Imbalance of ‘appetite hormones’ due to prolonged fasting.

Two main hormones control appetite (reference):

  • Leptin (the satiety hormone): a hormone that is secreted by fat cells, and it suppresses your appetite when you eat.
  • Ghrelin (the hunger hormone): It does the opposite action of leptin, as it increases when your body is deprived of food and stimulates your appetite.

Under normal conditions (fasting for a few hours), the ghrelin hormone increases gradually until you feel hungry.

However, if you don’t eat all day long, the ghrelin hormone may become inappropriately elevated and may cause side effects:

  • For people without stomach issues, it typically causes mild nausea with prolonged fasting.
  • For people with a pre-existing disease such as gastritis or stomach ulcer, very high ghrelin may cause severe nausea and/or throwing up.

Pre-existing stomach conditions may trigger vomiting while fasting.

As explained in the above section, the mechanisms such as acid build-up and appetite hormone imbalances often affect those with pre-existing stomach disease.

People with healthy stomachs are unlikely to vomit after not eating all day.

The most common disease that may contribute to vomiting with fasting include:

A. Chronic gastritis and peptic ulcer disease.

Chronic gastritis, stomach, and duodenal ulcers are the most common stomach disease. These diseases are often caused by NSAIDs, drug abuse, or an organism called H. Pylori infection.

Patients with gastritis or peptic ulcer often suffer from recurrent attacks of anorexia, upper central burning or gnawing pain, nausea, and/or throwing up.

Throwing up from not eating all day long is particularly common in patients with duodenal ulcers.

Learn more about gastritis and peptic ulcer disease.

6 Causes of Throwing Up Bile After Drinking Water.

B. Acute gastritis or acute gastroenteritis.

Acute gastritis or gastroenteritis is often due to infections (such as stomach flu) or food poisoning.

If the throwing-up onset is acute (not recurrent or chronic), always think of a stomach infection (acute gastroenteritis or stomach flu).

The most common cause of stomach infections is viruses (norovirus and rotavirus).

Learn more about acute gastroenteritis.

C. Chronic acid reflux (GERD).

Acid reflux is another very common disease to consider if your experience recurrent throwing up with heartburn.

Gastroesophageal reflux disease (GERD), or chronic acid reflux, is a widespread condition that causes the regurgitation of stomach acid into the esophagus.

Patients with GERD (acid reflux) commonly experience recurrent heartburn in the chest and regurgitation of acidic material to the throat or mouth.

Throwing up is more common in patients who lie down (without head elevation) for several hours in bed and those with hiatal hernia.

Learn more about GERD.

D. Stress or anxiety conditions.

The digestive system is often affected in people with chronic or acute attacks of anxiety, depression, or another psychological stressor.

Patients with severe anxiety (particularly the severe form) commonly experience anorexia (not eating all day long), nausea, and throwing up.

Learn More.

E. Eating disorders.

Eating disorders such as anorexia nervosa and bulimia nervosa are psychological disorders that affect many people.

These diseases are most common in young females with disturbed body images.

Patients with eating disorders such as anorexia nervosa may have prolonged periods of fasting as well as other digestive issues such as nausea, vomiting, and constipation.

F. Medications.

Taking medications on an empty stomach while fasting may cause nausea and throwing up.

Common offending medications are:

  • Nonsteroidal anti-inflammatory drugs such as aspirin and ibuprofen.
  • Some antibiotics, such as clarithromycin, penicillins, etc.
  • Opioid pain anoanorectalgesics.
  • Some antidepressants.
  • Oral contraceptive pills (OCPs).

Learn more.

G. Pregnancy and other female hormone fluctuations.

Fluctuations in female sex hormones (such as estrogen, progesterone, human chorionic gonadotropins, and others) are often associated with nausea and vomiting.

Common conditions that may cause vomiting in females include:

  • Pregnancy (particularly the first trimester).
  • During ovulation.
  • Before and during menstruation.
  • Hormonal contraceptive methods such as oral contraceptive pills.

H. Others.

The list mentioned above of possible causes is only the most likely cause, and it is not a complete list.

Other possible causes may include:

  • Gallbladder diseases.
  • Food intolerances.
  • Food allergies.
  • Pancreatitis (chronic or acute).
  • Neurological diseases such as migraine, brain cancer, hydrocephalus, etc.
  • Endocrinal diseases such as thyroid dysfunction, Addison’s disease, etc.
  • Kidney failure.
  • Diabetic ketoacidosis.
  • Recent operations (general anesthesia).
  • Cyclic vomiting syndrome.
  • And many others.

When to see a doctor:

See a doctor if:

  • The vomiting is persistent for more than a day.
  • Recurrent attacks of unexplained vomiting.
  • Severe upper stomach pain with throwing up.
  • Fever.
  • Severe abdominal tenderness.
  • Vomiting of blood or coffee-ground substances.
  • Passage of blood or black stool.

MORE:6 Causes of Brown, Coffee-Ground Vomiting On Empty Stomach.