Why Does Fast Food Make Me Feel Sick? (An In-Depth Look)

Fast food has become an integral part of modern life, offering convenience and instant gratification for our taste buds. From juicy burgers and crispy fries to mouthwatering pizzas and sugary sodas, these quick and easily accessible meals tempt many.

However, for some individuals, indulging in fast food comes at a price: a lingering discomfort and sickness. If you’ve ever wondered why fast food leaves you feeling queasy and unwell, you’re not alone.

Why Does Fast Food Make Me Feel Sick

In this article, we will explore the various factors that contribute to the common phenomenon of fast food-induced sickness, shedding light on both the physical and psychological reasons behind this uncomfortable experience.

Understanding these underlying causes can empower you to make healthier choices when it comes to your fast food consumption and overall well-being.

Table of Contents

Why Does Fast Food Make Me Feel Sick?

Fast food contains high levels of processed ingredients, chemical additives, sugar, and unhealthy fats that are difficult for the body to digest properly. This disrupts gut flora balance, causes inflammation in the GI tract, and leads to unpleasant symptoms like diarrhea, constipation, bloating, and nausea. Overeating fast food overwhelms the digestive system.

Why Does Fast Food Make Me Feel Sick: Top 10 Possible Reasons

Here are the top 10 reasons why fast food is likely to cause digestive distress and other unpleasant symptoms:

1. Food Processing Is Unnatural

Fast food ingredients are highly processed and contain additives to preserve flavor and shelf life. Heavily processed foods are foreign to the human body and difficult to digest properly.

The unnatural manufacturing processes strip away naturally occurring enzymes, vitamins, and fiber found in whole foods. This makes digestive upset more likely.

2. Food Additives Are Unnatural

Fast foods contain many chemical additives like artificial flavors, colors, preservatives, and emulsifiers. Common additives include MSG, nitrites, sulfites, BHA, and BHT. Some people are sensitive to these synthetic food chemicals and may experience headaches, gut irritation, and other reactions after consuming them.

3. Food Additives Are Harmful

Food additives like MSG and artificial trans fats in fast food are associated with adverse health effects. MSG may cause headaches and upset stomachs in sensitive people. Artificial trans fats in fried and baked fast foods promote inflammation, heart disease, and obesity.

4. Food Processing Uses Pesticides

Pesticide residues from conventional agricultural practices can remain on fast food vegetables, meats, and grains. Pesticides have been linked to various health problems, including headaches, nerve damage, hormone disruption, congenital disabilities, cancers, and damage to the gastrointestinal tract.

5. Hot Foods Can Upset Digestion

Fast food items like fried chicken, french fries, and burgers are often served blistering hot. This high temperature can irritate the digestive tract for some people, especially those with digestive conditions like IBS or GERD. Letting food cool down a bit before eating can help.

6. Fast Food Contains Chemicals

Besides food additives, fast food preparation and packaging involve chemicals like phthalates, flame retardants, and PFAS (per and poly-fluoroalkyl substances). These chemicals have been linked to hormone disruption, immune effects, developmental issues, and cancer.

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7. Fast Food Is High In Unnatural Fats

Fast food tends to contain unhealthy fats like processed vegetable oils, hydrogenated oils, and fried animal fats. These fats are difficult to break down and can damage the lining of the GI tract. They also disrupt satiety signals, leading to overeating.

8. Food Additives Will Harm Your Health

According to scientific studies, artificial colors, preservatives, and other food additives found abundantly in fast food have been linked to health issues like hyperactivity in children, cancer, asthma, hormonal changes and kidney damage.

9. Fast Food Imbalances Your Neurotransmitters

A diet high in processed foods like fast food leads to an imbalance in neurotransmitters – the brain chemicals that regulate mood, appetite, sleep, and cognition. This can lead to depression, trouble concentrating, cravings, and overeating.

10. Fast Food Increases Appetite

The glycemic load of fast food leads to surges and crashes in blood sugar. This causes reactive hypoglycemia, which increases hunger and promotes overeating. Fast food is also calorie-dense and nutritionally poor, making it easy to over-consume calories.

Why Does Fast Food Upset My Stomach?

If you often get stomach pain, diarrhea, bloating, or other gastric distress after eating fast food.


1. Fructose Is Hard To Digest

Fast food items like soda, fruit juices, sauces, and desserts are loaded with fructose and high fructose corn syrup. Fructose is challenging to absorb and ferments rapidly in the gut, leading to gas, diarrhea, and belly pain.

2. Trans Fats Are Difficult For The Body To Break Down And Process

The trans fats used for frying and baking fast food are artificial fats the body struggles to metabolize correctly. This can irritate the gut lining. Trans fats also suppress anti-inflammatory bile acids, promoting inflammation.

3. High Levels Of Bad Bacteria Can Cause Constipation

The ultra-processed foods in fast food meals feed harmful bacteria in the gut, allowing them to overgrow. This disrupts the microbial balance. Too many harmful bacteria cause problems like constipation, diarrhea, and inflammation.

4. Processed Foods Are Lacking In Fibre

Fast food meals are meager in dietary fiber since processing strips it away from ingredients like wheat. Fiber is necessary for healthy digestion. Constipation and conditions like hemorrhoids are more likely without adequate fiber.

5. Processed Foods Lack Digestive Enzymes And Friendly Bacteria

Enzymes that help break down fats, carbs, and protein are destroyed during high-heat processing of fast food ingredients. Beneficial probiotics are also absent. This forces the digestive system to work harder to break down and assimilate nutrients.

6. Many Fast Foods Are High In Sugar

Fast food meals tend to be loaded with added sugars through high fructose corn syrup, desserts, sauces, and soda. A diet too high in sugar disrupts healthy gut flora and causes yeast overgrowths, leading to indigestion.

7. Raw Vegetables Upset My Stomach

Salads and raw veggies at fast food places are often loaded with pesticides and served with high-risk toppings like salad bar croutons, onions, or hot bacon bits, which can irritate digestion. Stick to fully-cooked veggies when eating fast food.

8. Processed Foods Contain Harmful Chemicals

Fast food contains chemicals linked to digestive issues, from flame retardants leaching from wrappers to phthalates in plastic drink bottles. These chemicals harm gut health, and some cause diarrhea when consumed.

9. Processed Foods Contain Fats That Damage The Gut

Fast food french fries, chicken nuggets, burgers, and other items are high in processed vegetable oils, hydrogenated oils, and fried in refined oil. These oils promote inflammation and damage the protective mucosal lining of the GI tract.

10. Fast Food Contains Artificial Colours

Studies have linked artificial food dyes like Red 40, Yellow five, and Yellow 6, commonly found in fast food, to gastrointestinal upset, nausea, bloating, and other digestion issues, especially in children.

Why Does Fast Food Make Me Poop?

If you often get diarrhea soon after eating fast food, some potential reasons are:

1. Fructose Is Hard To Digest

The excess fructose in fast food overwhelms the transporters that allow fructose absorption across the intestinal wall. This leads to fructose malabsorption, which draws water into the colon, causing diarrhea.

2. Trans Fats Are Difficult For The Body To Break Down And Process

Artificial trans fats in fast food are associated with inflammation, gut permeability, and reduced levels of beneficial fecal bile acids – all factors linked to diarrhea and loose stools.

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3. High Levels Of Bad Bacteria Can Cause Constipation

Imbalances in the gut microbiome allowing pathogenic bacteria to thrive cause irritation along the intestinal lining, which can stimulate peristaltic contractions, leading to urgency and diarrhea after eating fast food.

4. Processed Foods Are Lacking In Fibre

Fast food often contains little fiber necessary to bulk up stools and slow digestion. Transit time speeds up without adequate fiber, resulting in looser bowel movements.

5. Processed Foods Lack Digestive Enzymes And Friendly Bacteria

The enzymes and probiotics typically found in natural food, which support proper digestion and gut function, are destroyed by food processing. Their absence leaves the gut unable to break down fast food properly and digest it efficiently.

6. Many Fast Foods Are High In Sugar

Excess sugar from high fructose corn syrup, desserts, and soda feeds gut microbes whose metabolism produces gas and causes osmotic diarrhea when large amounts remain undigested in the colon.

7. Raw Vegetables Upset My Stomach

Salad greens or veggies on fast food sandwiches are often full of pesticides, which damage gut lining integrity. This allows inflammation-provoking compounds into the bloodstream, which can stimulate diarrhea.

8. Processed Foods Contain Harmful Chemicals

Studies indicate chemicals used in processing, packaging, and preparing fast food, including phthalates, PFAS, and glyphosate residues, can cause damage to the mucosal lining of the GI tract, resulting in diarrhea.

9. Processed Foods Contain Fats That Damage The Gut

Oxidized, inflammatory oils used to cook fast food disrupt the intestinal barrier, leading to a “leaky gut.” This allows irritants and toxins to trigger inflammation and fluid secretion, causing diarrhea.

10. Fast Food Contains Artificial Colours

Colors like Yellow 5, Red 40, and Yellow 6 added to fast food have been found to cause allergic reactions resulting in diarrhea, especially in children and those with food sensitivities.

How To Feel Better After Eating Fast Food?

If you regularly get sick from eating fast food, try these tips to support your digestion:

  • Take probiotic supplements to replenish gut flora
  • Drink ginger tea to soothe inflammation and nausea
  • Include fermented foods like kimchi and sauerkraut for healthy probiotics
  • Use activated charcoal capsules to help bind and excrete toxins
  • Take digestive enzymes to help properly break down fast food meals
  • Drink plenty of water to stay hydrated and support detoxification
  • Reduce sugar and unhealthy fats to avoid further damaging your digestion
  • Eat more whole plant foods like fruits, vegetables, legumes, nuts and seeds
  • Limit fast food meals and make healthier choices when possible
  • Exercise regularly to reduce inflammation and support gut motility

The key is moderating fast food intake and focusing on a healthy, whole-food diet. It’s also wise to see a doctor to rule out issues like food allergies, inflammatory bowel disease, or chronic infections. You can start feeling better after eating fast food with some digestive care strategies.

The Bottom Line

Fast food makes many people feel sick due to high levels of sugar, unhealthy fats, chemical additives, and synthetic ingredients foreign to the body.

Overeating fast food disrupts the gut microbiome, causes inflammation, damages the GI lining, and leads to issues like diarrhea, constipation, bloating, and nausea.

Limiting fast food intake and emphasizing nutritious whole foods, probiotics, and digestive enzymes can help minimize adverse reactions.

When possible, it’s wisest to avoid fast food and opt for fresh, high-quality foods to support optimal digestive health.


How do I stop feeling sick from fast food?

If you’re feeling sick after eating fast food, there are a few things you can do to help alleviate the symptoms:
Stay hydrated: Drink plenty of water to help flush out any excess sodium and toxins from your system.
Avoid other trigger foods: If you know that certain foods or drinks make you feel worse, such as caffeine or spicy foods, avoid them until you’re feeling better.
Rest: Give your body time to rest and recover by taking a nap or getting restful sleep.
Eat lighter, healthier meals: Choose lighter, more nutritious meals that are easier for your body to digest, such as fruits, vegetables, lean proteins, and whole grains.
Avoid fast food: If you consistently feel sick after eating fast food, it may be best to avoid it altogether or limit your consumption to occasional treats.
Consider consulting a healthcare provider: If you’re experiencing persistent symptoms, such as nausea, vomiting, or diarrhea, it’s a good idea to consult a healthcare provider to rule out any underlying conditions or food sensitivities.
Remember, fast food is often high in unhealthy fats, sodium, and processed ingredients, and it’s generally not a healthy or balanced source of nutrition. Choosing healthier options can help you avoid feeling sick after eating and can also help improve your overall health and well-being.

Why does McDonald’s make me feel sick?

There are several reasons why McDonald’s (and other fast food) may make you feel sick:
High in fat and calories: McDonald’s food is often high in unhealthy fats, such as trans fats and saturated fats, as well as calories. Consuming too much of these can be difficult for your body to digest, leaving you feeling bloated and uncomfortable.
High in sodium: McDonald’s food is also often high in sodium, which can cause your body to retain water and lead to bloating and discomfort.
Processed ingredients: Many McDonald’s menu items contain processed ingredients, preservatives, and additives that can be hard for your body to process and may cause digestive discomfort.
Lack of fiber: Many McDonald’s menu items are low in fiber, slowing digestion and making you feel sluggish and uncomfortable.
Food sensitivities: Some people may have a sensitivity or intolerance to certain ingredients commonly found in McDonald’s food, such as gluten, dairy, or soy.
It’s also important to note that everyone’s body is different, and what may make one person feel sick may not have the same effect on someone else. Suppose you consistently feel sick after eating McDonald’s. In that case, it may be a sign that your body cannot tolerate the ingredients or nutritional composition of these types of meals, and it may be best to limit your intake or avoid them altogether.

My name is Shayon Mondal, and I am the proud owner of Foodsvision, a vibrant and delicious food blog. At Foodsvision, we believe in the power of food to bring people together and create memorable experiences. Join us on this culinary journey as we explore diverse flavors, share mouthwatering recipes, and celebrate the joy of cooking. Get ready to tantalize your taste buds and embark on a delightful adventure with Foodsvision! And more info page https://foodsvision.com/about-shayon-mondal/

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