Loss Of Appetite With IBS: 8 Causes Explained.

Welcome to The most unpredictable, irrational, and exhausting disease in the world. It is called “irritable bowel syndrome”.

But I prefer to call it “irrational bowel syndrome”.

Hi, I’m Dr, Farahat, a gastroenterologist and IBS sufferer.

Here, you will learn the full stack about Your IBS, Not just some random advice or recipes.

I’ll take you on a deep journey to understand the link between your IBS and anorexia from my own perspective as An IBS sufferer and gastroenterologist.

Today I will answer some questions about your IBS & appetite loss.

  • Can your IBS cause loss of a petite?
  • What is the link between IBS and appetite loss?
  • How to know the specific cause of your lost appetite?
  • What are the warning signs that you shouldn’t overlook?

This is Part One of a two-part series about the loss of appetite and IBS.
In part 2, I will provide you with a full Step-by-step action plan to REGAIN your appetite with IBS.

Can IBS cause a loss of appetite?

A lost appetite is not a cardinal symptom of IBS. IBS primarily affects your colon. However, many factors related t IBS (such as anxiety, abdominal pain, and others) can indirectly result in lost appetite.

The main symptom of IBS is abdominal pain, associated with a change in stool frequency or form. The Rome IV criteria for the diagnosis of IBS didn’t include anorexia (loss of appetite) as a symptom of IBS.

Irritable bowel syndrome is referred to as a “functional” disorder. To date, we (doctors) don’t know The actual cause of functional gastrointestinal diseases including IBS.

IBS can Co-exist with other functional gut diseases, and many of them can cause loss of appetite.

Loss of petite (anorexia) is one of the disordered eating patterns. Research indicates that IBS raises the odds of having disordered eating patterns more than 7 times!

This study shows you that disordered eating patterns among IBS sufferers range from 15-25%. Compared to only 3% among the general population (ref)

8 Important questions to ask yourself to define The cause of lost appetite:

1- First, ask yourself: For how long?

The time frame of your appetite loss is very important in defining the specific cause. Basically, 99% of the time, your anorexia will fall under one of the 3 below patterns:

  • Chronic anorexia: loss of appetite for longer periods. Usually months or even years.
  • Acute anorexia: you recently experienced a loss of appetite, usually for days.
  • Recurrent anorexia: your appetite swings with days of a good appetite and others with a lost desire for eating. The attacks of anorexia may be associated with IBS flare-ups.

Chronic anorexia may indicate that you have psychological problems such as chronic stress or anxiety.

Also, it may occur due to associated other functional gut disorders such as functional dyspepsia, functional nausea & vomiting.

If you have a chronic loss of appetite, it is better to discuss the issue with your doctor in the next visit.

Also, tell your doctor about any chronic medications as many of them can lead to loss of appetite?

Recent appetite loss may indicate mild infection ( such as viral gastroenteritis), new medication, or recent stressful situations (such as upcoming exams).

Usually, losing appetite for a day or a few days for The first time is not a cause of concern unless:

  • It becomes prolonged for weeks.
  • Related to the introduction of a new chronic medication or supplement.
  • Associated with other atypical symptoms such as fever, vomiting, intense comics that are not typical for your IBS.

Recurrent Anorexia occurs as “Attacks” of appetite loss that come and go with your IBS flare-ups. It is usually a response of your body you IBS Pain. And It disappears after the IBS flare-up goes away.

In cases, Your IBS can result in a condition called ” ARFID” or “avoidant/restrictive food intake disorder” (explained below).

2- Is it your Mind or your gut? (The most common & most underrated cause of both IBS and loss of appetite).

Do you Notice that your IBS is Greatly triggered by your constant fear and anxiety?

Do you have atypical symptoms associated with Your IBS? Such as:

  • Nausea
  • Loss of appetite (anorexia).
  • Shortness of breath (difficulty breathing)
  • Unexplained fatigue
  • Restlessness
  • Insomnia.
  • Atypical IBS pain locations such as chest pains back pain, or pelvic pain.

If you have one or more of the above symptoms associated with your IBS, The odds of anxiety increases.

Anxiety is very common with IBS. This study estimates that 44% of IBS patients have anxiety (compared to 8% among non-IBS patients ).

anxiety and ibs prevalence

The hallmark of anxiety is an irrational fear and worrying about normal daily events. Associated symptoms may include headaches, restlessness, sweating, and rapid heartbeats.

In severe cases, anxiety may interfere with your daily activity and an eating class of appetite and nausea).


If you think you have anxiety, it is better to evaluate yourself by this online test at online-therapy.com to define how much your anxiety can affect your IBS.

If you test positive, then anxiety is the most likely cause of loss of appetite with your IBS.

3- Do you have a “Disordered Eating” or “Eating Disorder”?

“Disordered Eating” is different from “Eating Disorders.”


An “Eating Disorder” is a real Pathological and Psychological disease. The disturbed eating  causes significant impairment of your physical or psychological health, such as:

  • Severe weight loss or weight gain.
  • intense fear of gaining (or losing) weight.
  • distorted perception of your body image.

common defined “eating disorders include:

  • Anorexia Nervosa.
  • Bulimia Nervosa.
  • ARFID (Avoidant/Restrictive Food Intake Disease).
  • Pica
  • Rumination disorder

the “eating Disorder” is of a psychological nature. and usually associated with other psychological diseases such as anxiety and depression.

The term ARFID “Avoidant/Restrictive Food Intake Disorder,” was first introduced in 2013 to describe” fear of food consequent as such as pain or diarrhea” (ref). your Brain becomes extremely picky in choosing food.

AFRAID Can occur with IBS. The condition is usually severe and may Be associated with weight loss, dependence on nutritional supplements.

This condition is common among children, but also it can occur in adults with IBS.

How to suspect ARFID?

  • The fear associated with Food consequences, as it may trigger your IBS.
  • Avoiding contain food based on smell, color, or any Food characteristic.
  • Significant food loss.
  • Dependence on supplements.
  • Significant nutrient deficiency.
  • Presences of psychological problems such as anxiety.
    ARFID is a real disease that requires medical help. Consult your doctor if you suspect ARFID.


“Eating disorders” is the severe form of “disorder eating”. “Disordered eating” is a milder, less debilitating condition in which you may suffer from abnormal appetite or feeding behavior.

But usually doesn’t cause significant effects on your weight and health.

Examples of disordered eating pattern that may cause loss of appetite with IBS:

  • Prolonged fasting.
  • Skipping Meals for fear of your IBS.
  • Very restrictive dieting
  • Unbalanced eating (restricting major food group)
  • abusing laxatives, or diet pills.

All the above patterns can cause a loss of appetite with your IBS.  Being unable to cope with a stressful situation or having anxiety is a major cause of “disordered eating”

4- Do you have Another Functional gut disease (co-existing with your IBS)?

Having IBS raises your odds of getting another associated functional gastrointestinal disease.

And this is another Common cause of loss of appetite with IBS. Common conditions that can cause anorexia with IBS include (ref):

  • Functional dyspepsia (also known as indigestion): symptoms including stomach pain, bloating, nausea, and maybe a loss of appetite.
  • Chronic idiopathic nausea
  • Functional heartburn.
  • Functional gallbladder disorders.
  • Functional abdominal bloating and distension.
  • Unspecified functional bowel disorders.

The list goes on with functional gut disorders. But the above-mentioned types are the most likely to cause loss of appetite with IBS.


Functional dyspepsia is far the most common condition to be associated with IBS. Unfortunately, no specific test or imaging can diagnose such functional diseases. To be diagnosed with such conditions, only your doctor can do this after the exclusion of any organic diseases.

The diagnosis of functional gut diseases is based only on certain clinical criteria. This criterion is created by The “Rome Foundation” for gastrointestinal diseases.

When to suspect having other functional gut disorders as the cause of lost appetite?

  • Unexplained loss of appetite for a long time.
  • Unexplained nausea, bloating, epigastric pain, or early satiety.
  • Your symptoms are consistent with one of the functional disorders enlisted above, you can learn more here.

5- Do you take any of these medications that cause anorexia?

Another overlooked cause of losing appetite with IBS is The medications you take. Whether it is:

  • IBS medications.
  • Other medications you concurrently take for other diseases or conditions.

Yes! Some IBS medications May cause loss of appetite, for example:

  • Dicyclomine (Bentyl).
  • Hyoscomine (Anaspaz, Hyosyne)
  • Linaclotide(Linzess).
  • Lubiprostone (Amitiza).
  • Librax.
  • And others.

But please note that:

  • Taking one of the above drugs doesn’t necessarily mean it is The cause of your appetite loss.
  • Too many factors other than IBS medications can contribute to your anorexia.
  • Stopping your IBS medication on your own call lead to an IBS flare-up.
  • Always discuss The issue with your doctor. Especially the unset of your appetite loss is related to starting or changing the dose of a medication you take.


Some other medications can cause anorexia (loss of appetite), whether chronic or recent medications, common examples include:

  • Some antibiotics (such as Metronidazole)
  • Certain sedatives and antidepressants such as Fluoxetine.
  • Chemotherapy
  • Some asthma medications such as Salbutamol and Theophylline.
  • Some Heart medications such as Amiodarone, Acetazolamide.
  • Some anti-epileptic medications such as Topiramate.
Always work with your doctor to review the list of your medication to assess if any causing your anorexia.


6- Do you have any other disease/conditions that co-exist with IBS and cause loss of appetite?

A simple way to think of the loss of appetite with IBS is to search for another associated disease or condition that may be the cause of your anorexia.

common conditions that can co-exist with IBS and cause anorexia:

  • Associated Gastritis, GERD, or Peptic ulcer: Any stomach inflammation can cause loss of appetite and the condition is very common and frequently exists together with your IBS, the hallmark of gastritis is “burning epigastric pain” related to meals. learn more here
  • Recent Gut infections: think of this cause if you have a RECENT loss of appetite for a day or a few days. commonly viral gastroenteritis, or any other form of gastro-enteritis or gut bugs. usually, the condition is associated with new-onset of diarrhea, yellow or greenish stools,  abdominal colics, vomiting, and maybe low-grade fever.
  • Any other infections elsewhere: any infection whether it is the recent or chronic infection can lead to anorexia. Common examples include flu, cold, respiratory infections, HIV, and others.
  • Some chronic diseases: Common examples include Diabetes Mellitus (causes a condition called diabetic gastroparesis), Chronic liver or Kidney diseases, High calcium levels in the blood, underactive or overactive thyroid gland, Heart failure, cancers, and Chronic obstructive pulmonary disease.

7- Do your “female hormones” play a role?

Nausea and anorexia are very common among females with hormonal disturbances. frequent conditions associated with anorexia include:

  • Recent undiscovered Pregnancy: a recent pregnancy can cause your lost appetite, suspect if you are a female in a child-bearing period, especially if you have a missed period. Test yourself at home for pregnancy if you’re not sure. Learn more about how pregnancy and IBS interact here.
  • Hormonal imbalances: any disturbance in female sex hormones such as during the peri-menopausal period can lead to swings in your appetite.
  • Birth control pills or any other hormonal method of contraception can contribute to loss of appetite.

8- Do you have any warning signs with the loss of appetite?

loss of appetite is usually a mild and temporary condition in the majority of the time. But if it persists or causes other serious symptoms you have to ask for help from your doctor.

common warning signs that require seeing a doctor for your anorexia and IBS:

  • Extreme loss of appetite for longer periods (more than a week), suggesting an “eating disorder”.
  • Progressive and significant weight loss. (suggesting an eating disorder or hidden organic disease such as cancers)
  • The onset of anorexia is associated with the introduction of a new medication (or changing the dose of an old medication).
  • Associated Unexplained fever.
  • Any other associated symptoms that are not typical for your IBS include blood in the stool, vomiting, irregular or fast heartbeats, extreme dizziness, or vertigo.

How can you (exactly) define your specific cause and regain your appetite again?

READ PART 2 of this series, I made an in-depth, step-by-step guide that will:

  • help you Easily Identify Your specific cause of anorexia with IBS.
  • Exclude serious illnesses and conditions.
  • Help you assess the need for medical attention, and warning signs.
  • Help you Regain the desire to eat be defined steps, with exact food strategy, supplement, and medication Plan.
  • This is the only and the most comprehensive guide you’ll EVER NEED.

Proceed to Part 2 of this series to learn the Step-by-Step action plan to regain your appetite again with IBS.m