Loss Of Appetite With IBS: 7 Causes Explained

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Ah, IBS. Or as a sufferer would call it, “my worst nightmare.” This disease is one that can really take its toll on you, and it goes under the guise of a relatively benign name “irritable bowel syndrome.” 

We’re here to give you all of the information that you need on this medical issue to make your life just a little bit easier.

Today, we’re going to show you some of the links between IBS and loss of appetite, and how IBS and anorexia are linked.

Is My IBS Causing My Lack of Appetite?

It’s easy to assume that IBS is the cause of your poor appetite since it affects your bowels, but no – it’s actually not a key symptom of IBS.

The illness primarily targets your colon. With that being said, that doesn’t mean losing your appetite thanks to IBS is completely out of the realm of possibility.

IBS can cause a lot of other symptoms, like abdominal pain, bloating, and gas – making you feel like you don’t want to eat. Some people may be scared to eat, because they will be running to the bathroom afterwards.

As any IBS sufferer will know, abdominal pain is the main issue.

This is usually thanks to the change in how often you have a bowel movement. It’s important to note that you won’t find anorexia – or loss of appetite – listed on the standard criteria for an IBS diagnosis.

This disorder is what is known as a ‘functional’ one. Even today we don’t even know what causes these sorts of functional gastrointestinal disorders. Go figure! 

IBS can often appear in conjunction with a few other functional gut diseases. Many of these illnesses will result in a loss of appetite too. 

Anorexia, or loss of appetite, is known as a kind of disordered eating pattern that can result from many different medical conditions. Anorexia nervosa is a little bit different.

This is an eating disorder, characterized by someone who is underweight (or not growing adequately in childhood/adolescence), has an intense fear of gaining weight, and a distorted perception of their weight.

Roughly 15-25% of IBS sufferers have disordered eating patterns – a staggering number when you consider that only 3% of the general population (without IBS) will get them.

A Few Things to Ask Yourself to Figure Out Why You Have Lost Your Appetite

1. How Long Has It Been Since You Lost Your Appetite?

It will be a lot easier to figure out why you have lost your appetite if you know the time frame of when it developed.

For the vast majority, there are 3 main patterns that your appetite loss will fall into:

  • Chronic anorexia – this is when you lose your appetite for much longer periods of time. This can often be for months and sometimes even years on end.
  • Acute anorexia – this is when you experience a recent appetite loss and it tends to only last for a couple of days
  • Recurrent anorexia – sometimes you have days with a good appetite and others you may struggle to eat. Sometimes the anorexia can be linked with flare-ups of your IBS.

If you have chronic anorexia then it’s worth looking into psychological causes like anxiety or depression, or even an eating disorder, like anorexia nervosa. They can often be a culprit.

Sometimes the anorexia can occasionally appear thanks to other kinds of functional disorders of the gut. Some examples include functional nausea and vomiting and functional dyspepsia. 

You should always visit your doctor for more information if you are experiencing chronic anorexia or weight loss.

Make sure that you tell your doctor about any medications that you are taking on a consistent basis. There are some that may be causing your lack of appetite.

If you are experiencing recent appetite loss, especially with a sudden onset, then there’s a chance that you may have an infection such as a stomach virus, or you may have started a new medication.

Sometimes it can come as a result of situations in your life that are causing you stress like upcoming exams, a big work presentation, or even a first date.

You don’t usually need to be too worried if you just lose your appetite for a day or two for the first time. Of course, there are always exceptions to the rule, such as:

  • If the appetite loss starts to last for a number of weeks
  • If it begins after starting a new supplement or medication
  • If it comes along with other abnormal symptoms such as vomiting, fever or weight loss

2. What’s Causing The Appetite Loss – Your Gut Or Your Mind? 

One thing that you may notice is that your IBS may flare up more frequently if you are feeling anxious or stressed.

Symptoms that aren’t typical for IBS may mean there is something else going on.  These atypical symptoms could include:

  • Struggling for breath
  • Chest tightness
  • Restlessness or agitation
  • Irritability
  • Nausea
  • Excessive tiredness
  • Pain in uncommon areas like your pelvis or back

If you are noticing one or more of these symptoms then there’s a good chance some other condition is also at play.  If you have chest tightness or struggle for air, call your doctor ASAP or go to the emergency room.  Sometimes, this may just be anxiety, but we don’t want to miss more serious conditions like a heart attack or blood clot.

A staggering number of people experience anxiety alongside IBS. Almost 50% of IBS patients also experience anxiety, which is a pretty big percentage in comparison to the general population where just 8% experience anxiety.

Anxiety is usually characterized by excessive fear and worrying on a regular basis, sometimes over normal occurrences in everyday life. Sufferers may sometimes experience symptoms such as sweating, restlessness, headaches and racing heartbeat.

In some really bad cases of anxiety, it can disrupt your life. In some cases, that may result in feeling sick and losing your appetite.

There are, of course, some things that you can do. The main thing to start with though, is to evaluate whether you have anxiety and try to find activities like exercise or meditation to help cope with stressors to reduce your anxiety. 

You can check with your doctor about your anxiety symptoms, especially if you have trouble managing it with lifestyle changes. There are also online tests – some will even help you to determine the level at which your anxiety will affect your IBS.

If you do find that you have anxiety then there’s a good chance that it’s the reason that you have lost your appetite.

3. Work Out If You Have Disordered Eating Or If You Have An Eating Disorder

It’s very important to note that there is a big distinction between eating disorders and disordered eating.

So What Is An Eating Disorder?

In short, it’s a serious psychological and pathological illness. It can result in disturbed eating and it can cause some major problems both for your physical and mental health. For instance, you may find yourself gaining or losing excessive amounts of weight. You may find that you are also struggling with your body image and you have a very strong fear of weight gain.

There are a number of eating disorders out there, including bulimia nervosa, anorexia nervosa, pica, ARFID (avoidant/restrictive food intake disorder) and finally, rumination disorder.

Eating disorders are primarily a psychological issue, and they often tend to occur with other mental health concerns like depression and anxiety.

ARFID, or avoidant/restrictive food intake disorder was a term coined back in 2013. It essentially means a fear of the consequences of eating like diarrhea or pain. You begin to struggle to eat certain foods and can drastically alter your diet, resulting in weight loss and nutritional deficiencies.

This particular eating disorder can be quite common with IBS. It’s a very severe problem and sometimes can be associated with losing excessive amounts of weight and over dependence on supplements. It is a condition that is more common in children, but it can also happen in adults suffering from IBS.

There are a few symptoms that you should be on the lookout for to rule out ARFID:

  • Trying to avoid particular foods, generally based colors, smells, taste or texture 
  • Losing food – may be through vomiting etc
  • Fearing that eating will trigger IBS symptoms
  • Over reliance on food supplements
  • Nutrient deficiencies
  • Anxiety and other psychological issues

Disordered Eating

So now we’ve covered what an eating disorder is, what is disordered eating? In essence, everything that we have covered above is a much more extreme version of disordered eating. Generally disordered eating isn’t nearly as catastrophic for your body.  You may find that your appetite is a little unusual, as are your eating habits.

In most cases, disordered eating won’t cause any major problems for your health and weight.

There are a couple of disordered eating patterns that you may get with IBS, and many of them can cause you to lose your appetite. For instance: 

  • Longer periods of fasting
  • Restrictive eating
  • Skipping some meals out of fear of an IBS flare up at an inopportune time
  • Eating in an unbalanced way, for instance omitting a certain food group from your diet
  • Using products like diet pills or other kinds of laxatives when they don’t need to be used

As you can most likely imagine, all of these things can result in appetite loss alongside your usual IBS. If you are struggling with anxiety or a certain stressful situation in your life then that could be a big reason for your disordered eating.

4. Are There Any Other Functional GI Disorders That You Have In Addition To IBS?

Unfortunately, if you already have IBS then there’s a much higher chance that you may develop other functional gastrointestinal disorders. Some of these can also result in losing your appetite. There are a few conditions that can result in loss of appetite alongside your IBS, including: 

  • Chronic idiopathic nausea
  • Functional heartburn
  • Functional gallbladder disorders
  • Functional abdominal bloating and distention
  • Functional dyspepsia or indigestion

There are a plethora of additional issues that you may get alongside IBS, but these are just a few of the main ones that can often result in a loss of your appetite.

When it comes to IBS and loss of appetite, functional dyspepsia is most often the one that crops up. There are no ways at present to diagnose most functional diseases with specific tests or procedures.

The only real way to be diagnosed with conditions such as these is to be assessed by your doctor who will see if your symptoms fit with the diagnostic criteria.  They will usually exclude any organic diseases first.

You will often find that functional GI disorders are diagnosed solely based on kinds of clinical criteria that your doctor may notice. These criteria were created by The Rome Foundation, who also have diagnostic criteria for IBS.

How can you know if another functional gut disorder is potentially causing your poor appetite? Well, you may notice that you have lost your appetite for a long period of time. Perhaps you are dealing with early satiety (getting full easily), nausea, bloating or upper abdominal pain. Finally, you may also notice that the symptoms you are experiencing seem to fit the diagnostic criteria for the other functional disorders mentioned above.

5. Are You Taking Any Medications That Can Result In Loss Of Appetite?

One thing that people often fail to think about is the fact that their medication may be causing them to lose their appetite.

You may lose your appetite because of your IBS medications or because of any other medications that you may be taking for other conditions. Read more about Good IBS Medications.

Certain types of IBS medications can result in a loss of appetite. For instance, hyoscyamine, dicylomine, linaclotide, librax, and lubiprostone may result in a loss of appetite.

There is one thing worth noting however. You may take these medications and it doesn’t mean that it simply must be the reason you have lost your appetite.

This is because there are many reasons besides your medications that can make you lose your appetite. It’s not a good idea to stop taking the medication without medical assistance since it can often result in a flare up of your IBS.

Check with your doctor if you think one of your medications is causing a loss of appetite.

There are also a couple of other kinds of medication that can result in appetite loss. These can be temporary medications or ones that you take permanently.

For instance, some antibiotics can cause nausea, indigestion or loss of appetite. So can antidepressants, sedatives, chemotherapy, some asthma medications, certain heart medications, certain anti-seizure medications.

It’s a good idea to speak with your doctor and go through the list to work out which one, if any, is causing your loss of appetite.

6. Are There Any Other Conditions Or Diseases Present That May Be Present Alongside The IBS?

Before automatically assuming that the appetite loss is occurring thanks to your IBS, it is first a good idea to look for other diseases or conditions associated with it that may be causing the problem.

For instance, acid reflux, gastritis (inflammation of the stomach) and stomach ulcers can be common culprits of appetite loss. If your stomach is inflamed you may be more likely to experience a loss of appetite.

In addition to this, things like gut infections that you have recently experienced can cause appetite loss. Infections in other parts of the body, like sinus infections or urinary tract infections, can also be a cause of poor appetite.

7. What About Your Hormones?

Your hormones can play a large role in your appetite, especially if you are female.

For instance, if you are pregnant but don’t know about it yet then that could potentially be a reason as to why you have lost your appetite. Make sure that you take a pregnancy test to figure it out!

Not only that, but any kind of hormonal imbalance can cause a loss of appetite.  Hormone levels fluctuate throughout the menstrual cycle, so you may notice that your loss of appetite always comes just before your period, for example.

Other things that can interfere include birth control pills or other kinds of hormonal contraception.

Know the Warning Signs

For the most part, people will generally only experience a loss of appetite for a short period of time. It’s worth keeping an eye out for potential problems though as you will need to speak to your doctor. This includes:

  • You have appetite loss induced by a new kind of medication
  • Long periods of extreme appetite loss – this could be indicative of an eating disorder
  • Unexplained fever
  • Symptoms that aren’t usually correlated to your IBS like blood in the stool
  • Persistent nausea and vomiting
  • Unintentional weight loss 

For more articles on living with IBS, check these articles out:

Written and Medically Reviewed By

  • Kelly Chow

    Kelly first experienced IBS symptoms at the age of 24 with major-to-severe symptoms. She underwent all types of tests and experimented with many treatments before finally finding ways to manage her symptoms. Kelly has written and shared ebooks and Gluten-Free diet plans that she has used to live life like she did before IBS.

  • Julie Guider, M.D.

    Dr. Julie Guider earned her medical degree from Louisiana State University School of Medicine. She completed residency in internal medicine at the University of Virginia. She completed her general gastroenterology and advanced endoscopy fellowships at University of Texas-Houston. She is a member of several national GI societies including the AGA, ACG, and ASGE as well as state and local medical societies.

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