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Writer's pictureStephanie Lum

Why Do I Feel Sick After I Eat?

Updated: Aug 6

Chronic discomfort - whether it manifests as headaches, nausea, or a general feeling of illness - can easily sabotage your quality of life and can make the daily task of eating a torment.


Unfortunately, many general practitioners quickly dismiss uncomfortable digestive symptoms once serious underlying conditions are ruled out, leaving patients to self-treat.


Once the underlying cause of the problem has been identified, there is often a clear path forward, often without the use of pharmaceuticals. A mysterious symptom is simply one that has not been adequately investigated.


Our consultation practice centers on functional medicine and offers specialized testing as well as natural and effective treatments that can mitigate the wide variety of symptoms that can occur during or after you eat.


Jan van Huysum's Fruit Piece Painting with text overlay Dr. Brian Lum

How Do You Feel Sick After You Eat?


Some patients experience symptoms upon ingestion - an immediate draining of energy, fullness in the sinuses, a migraine or headache, rapid heart rate, dizziness, nausea, as well as a general feeling of illness.  


Others may experience these symptoms while their food is digesting hours after they eat.  Additional symptoms could include fatigue, nausea, anxiety, insomnia, a sensation that food is not leaving the stomach, bloating, diarrhea, or constipation. 


Still other patients could be experiencing a persistent low level of inflammation so that they never feel well, but they notice that certain foods make them feel worse.  This consistent inflammation can make it very difficult to rule out what exactly is causing their symptoms, as symptoms can also be exacerbated by exercise, weather, stress, and seasonal changes.


The Body Is An Interconnected System 


In the West, we are conditioned to see the body as separated into quadrants, with each operating independently from each other. Medical specialties are separated in this way—we have heart specialists, ear, nose, and throat doctors, oncologists, and podiatrists.


Drug commercials promise to ‘shut off’ an obtrusive symptom like a switch as if it were the result of nothing more than a single faulty code in an otherwise well-functioning operating system.  


Seeing your body as a highly sensitive interconnected system is a more helpful and accurate conceptualization.  Phrases like ‘gut-healing,’ ‘brain-boosting,’ and ‘immune system strengthening’ are often used for marketing but seldom give a medically accurate picture of a solution. 


Your microbiome, for instance, stretches far beyond your intestinal tract - from mouth to anus - and everything from the viscosity of the mucus in your sinuses to the quality of your sleep to the delicate balance of the bacteria in your small intestine is vitally important to its function.   


A parasitic infection, for instance, while often producing type 2 allergic responses, can also suppress allergies via regulatory pathways. It is even theorized that the worldwide reduction in parasitic infections is correlated with an increase in allergic diseases. [1]


The balance of bacteria in your intestines not only can directly cause symptoms like headaches and fatigue but can also affect the presentation of severe mental illness. [2


Non-celiac gluten sensitivity (NCGS), a condition often dismissed as not having broader medical implications, has been shown to contribute to autism, schizophrenia, and depression and has been implicated in causing psychosis in case studies. [3


Usually, the solution for many digestive symptoms lies in looking beyond the obvious contributing factors.  Even when the cause is something seemingly simple - like low stomach acid - natural solutions can be extremely effective as long as they are administered correctly.


Common Causes of Feeling Sick After You Eat 


1. Food Sensitivities and Intolerances

One of the most common causes of symptoms like nausea, racing heartbeat, and fatigue after eating is a food intolerance (also called a food sensitivity).


Symptoms of a food intolerance can present immediately upon ingestion but can also be delayed by hours or even days. This delay can make the identification of food intolerances very difficult. 


While food allergies are generally more serious and can cause symptoms like a numb mouth, severe stomach cramping, swollen tongue, or anaphylaxis - the symptoms of food sensitivities are generally more subtle. It is important to note, however, that the symptoms of an intolerance can compound over time, leading to extreme ill health. 


Food intolerances are more common than food allergies and are largely underdiagnosed.  Usually, the symptoms seem subtle because people have had a low level of inflammation almost constantly for months or years.  


These patients feel so generally unwell most of the time that it can be hard for them to distinguish what exact food is making them sick until they remove it from their diet.   


Low-grade inflammation caused by food intolerances can lead to symptoms like fatigue, brain fog, weight gain, panic attacks, anxiety, depression, mood swings, blood sugar regulation issues, and migraines.  


Other symptoms can be more abstract and difficult to articulate. These can include a feeling of being poisoned, a feeling of impending doom, and increased neurological symptoms with changes in weather. 


Elimination trials are useful in which the suspected foods are strictly removed from a diet for at least two weeks but ideally six weeks.  This allows enough time for the low levels of inflammation to dissipate. 


When the food is reintroduced (in a very small amount in the morning on an empty stomach), it becomes very obvious if the food was the cause, as symptoms can return almost immediately. Elimination diets should not be done in the case of a suspected allergy, and these trials should only be done when working closely with your doctor. 


It is important to note that food sensitivity is not an adequate underlying cause, even if we find it.


The cause of the sensitivity is often a compromised intestinal lining and imbalanced liver detoxification, which can be caused by a wide range of factors, including toxin exposure (especially mold exposure), low stomach acid, or an autoimmune disease.  


In cases of suspected food intolerances, we often order testing to investigate underlying factors, remove the suspected foods from the patient’s diet, and work on healing the digestive tract. 


2. Infection

A parasitic, fungal, bacterial, or viral infection can all cause you to feel sick after you eat.


Testing can determine the strain and location of the infection, which will inform the best primary treatment to kill the infection and the best secondary interventions (such as diet, supplements, and lifestyle changes) to speed up recovery.  


One of the most common types of infections that produce symptoms after eating is small intestinal bacterial overgrowth (SIBO) - the primary symptoms of which include abdominal bloating and diarrhea. 


SIBO can be caused by antibiotic use, poor diet, or food poisoning, which can allow undesirable bacteria to overrun the small intestine.  


In the case of a parasitic infection, the eggs and larvae can become lodged in your liver and digestive organs, causing symptoms every time you eat.


Often, these types of underlying infections do not have the classic signs of infection (like fever and chills) but can have significant symptoms and can last for months or years when left untreated.


Lesser-Known Symptoms Of Infection
  • Brain Fog

  • Stomach pain, cramping

  • Headaches

  • Migraines

  • Rectal Itching

  • Irritability

  • Fatigue

  • Lethargy

  • Skin Rash

  • Eczema

  • Rosacea

  • Autoimmune-like symptoms

  • Body temperature regulation problems

  • Blood sugar regulation problems


Specific Food Reactions 

In some cases, symptoms that arise after eating certain foods can indicate a specific underlying problem. In these cases, the food you are eating is fueling an underlying infection.


These categorizations are very general and should not be used to diagnose yourself. Remember that there are always exceptions to every medical classification - including these.


Mold Exposure, Bacterial & Fungal Infection

Viral 

You May Particularly React To:

  • Eggs

  • Dairy

  • Sugar

  • Corn

  • Wheat/Gluten 


Bacterial 

You May Particularly React To:

  • Eggs

  • Dairy

  • Wheat/gluten

  • Sugar 

  • Onions, Garlic, cruciferous vegetables, and other high-FODMAP foods 

  • Lentils and beans

  • Leftovers


Mold Exposure and Fungal 

You May Particularly React To:

  • Sugar

  • Fruit

  • Dairy 

  • Corn 

  • Eggs 

  • Wheat/gluten 

  • High Histamine Foods (like vinegar, fermented foods, dairy, leftovers, tomatoes, and smoked meats)

  • Peanuts and other nuts 

  • Mushrooms

  • MSG

  • Soy

  • Preservatives 


Parasitic Infection

You May Particularly React To:

  • Pork

  • Seafood 

  • Corn 

  • Sugar

  • Dairy

  • High Histamine foods 


3. A Liver and/or Gallbladder Problem

Another common problem that can cause you to feel sick when you eat is when your liver is not producing enough bile to properly digest your food. 


Bile contains acids that help break down food - particularly fat and fat-soluble vitamins. 


When bile production is too low, it leads to the malabsorption of essential nutrients. Low bile production is one of the primary reasons why people have recurrent SIBO.  Bile, along with healthy stomach acid production, is vital for motility and the prevention of bacterial buildup in the small intestine.


Even if these patients were to take the 'right' supplementation to reverse deficiencies, their digestion is often so impaired that they would not be able to absorb what they need.


A common symptom of gallbladder dysfunction is pain near the shoulder blades as well as morning nausea.  This can occur even if your gallbladder has been removed.


Stool and blood testing can be ordered to look at bile acids, and other testing is usually done to determine if nutritional deficiencies are contributing to symptoms. 


A surprisingly effective natural solution for many of these patients is to start off their day with the juice of half a lemon in a glass of warm water. In the short term, they would decrease their dietary fat while we worked to restore the normal function of their digestive tract. 


Again, however, working with a doctor is important as even natural remedies can cause ill effects if the right underlying cause is not being treated in the proper order or at the right time.


4. Low Stomach Acid

Low stomach acid can be caused by poor diet, not eating during an optimal window during the day and chronic stress. Chronic stress is the most common factor we see in our practice that compromises the production of quality stomach acid.


When there is not enough stomach acid to digest food, the body cannot absorb key vitamins and nutrients.


It can also lead to pieces of food festering in your digestive tract, creating gasses, and providing food for 'bad' bacteria.


In these cases, the first step is the same one that aids in bile production and involves taking the juice of half of a lemon in water about 15 minutes before each meal to aid digestion. If this is not tolerated well, other steps can be taken to improve stomach acid production.  


In our practice, a patient's diet is assessed after low stomach is confirmed. Herbs are often administered to assist digestion and facilitate stomach function. Alcohol-free herbal bitters can also be very useful.


Symptoms of Low Stomach Acid
  • nausea when taking pills

  • brittle nails (indicating a lack of absorption of minerals)

  • acid reflux

  • bloating

  • stomach pain and cramping

  • nausea after eating


5. Intestinal Sensitivity Syndrome

Inflammation and nerve sensitivity in the lining of the intestines can cause a wide range of symptoms every time you eat. 


Foods high in fiber, such as fruits, whole grains, and vegetables, can make symptoms worse in these cases.  


This can be very confusing for patients who have healthy diets but have severe digestive symptoms, as the ‘healthier’ they eat, the worse their symptoms get. 


One of the many potential causes behind intestinal sensitivity is a fungal or bacterial infection.


Our first step would be to temporarily adjust the diet so as not to aggravate the digestive system further.  We would then identify and kill any infection that is causing the inflammation while soothing the nervous system. 


We would then slowly increase the amount of fiber in the diet to ‘manually’ get rid of the waste of the infection.


The Herbs Of Functional Medicine

While treatment will vary widely depending on diagnosis, a few high-grade herbal supplements and healing foods are often included in many treatment plans. 


Always get these supplements from a functional medicine doctor. The supplements you see at the store and online can be of poor quality, contaminated with heavy metals, can contain the wrong form or quantity of herb, or can be counterfeit. 


Specificity matters - to achieve optimal benefit from any supplement, you need to take the right form, quality, and dosage for you.


Berberine, garlic, oregano oil, and olive leaf extract are frequently used to great effect when killing a bacterial or viral infection. One of these would generally be paired with other treatments so that they can work synergistically to kill the infection and repair the damaged tissues. 


Even when an antibiotic is required for your treatment, your doctor can pair it with an extract for maximum effect - olive leaf extract, for instance, has been shown to increase the effectiveness of antibiotics in certain cases. 


Soothing the nerves of the digestive system is a big part of reducing symptoms and inflammation. Lemon balm and marshmallow root are frequently used and can be taken in a tea or pill form. 


Once the infection is effectively on its way out the door, we often slowly increase the amount of dietary fiber to escort debris out of the intestinal tract.


To repair the intestinal lining, vitamin A, zinc, and marshmallow root can be excellent companions to primary treatment.


Remote Consultations For Persistent Symptoms 

Dr. Brian Lum, an IFMCP functional medicine practitioner, sees patients remotely from all over the world and is currently accepting new patients.


New patient appointments are an hour long, and follow-up appointments are 30 minutes. All pricing is listed on our website. Testing kits can be sent to most locations, and testing can be arranged through a local hospital or a blood draw location near you. 



If you would like to schedule a free 15-minute consultation with Dr. Lum to ask questions about becoming a patient, click the link below.



 

Written by Stephanie Lum with Dr. Brian Lum ensuring medical accuracy. 


Disclaimer: If you think that you may have a medical emergency, call your doctor or 911 immediately. No action or inaction should be taken based solely on the contents of this information. You should never delay seeking medical advice or treatment due to the information contained on this Website. The information on this Website is not intended to diagnose, treat, cure, or prevent any disease or medical condition. The information discussed is not intended to replace the advice of your healthcare provider. Reliance on the information provided by this Website, Dr. Brian Lum, or Functional Healthcare Institute is solely at your own risk.


Bibliography


[1] Cruz, Alvaro A., Philip J. Cooper, Camila A. Figueiredo, Neuza M. Alcantara-Neves, Laura C. Rodrigues, and Mauricio L. Barreto. 2017. “Global Issues in Allergy and Immunology: Parasitic Infections and Allergy.” Journal of Allergy and Clinical Immunology 140 (5): 1217–28. https://doi.org/10.1016/j.jaci.2017.09.005.


[2] Nguyen, Tanya T, Hugh Hathaway, Tomasz Kosciolek, Rob Knight, and Dilip V Jeste. 2021. “Gut Microbiome in Serious Mental Illnesses: A Systematic Review and Critical Evaluation.” Schizophrenia Research 234: 24–40. https://doi.org/10.1016/j.schres.2019.08.026.


[3] Lionetti, Elena, Salvatore Leonardi, Chiara Franzonello, Margherita Mancardi, Martino Ruggieri, and Carlo Catassi. 2015. “Gluten Psychosis: Confirmation of a New Clinical Entity.” Nutrients 7 (7): 5532–39. https://doi.org/10.3390/nu7075235.




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