What Are The 7 Worst Foods For Gut Health?

An image showing a list of fast foods; pizza, burger, soda, popcorn, hotdog, fried chicken and chips

If you have ever had a “gut feeling” or felt bloated after a big meal, you already know your digestive system is trying to tell you something.

Your gut is home to trillions of bacteria, fungi, and viruses which collectively are called the microbiome. The microbiome helps digest your food, train your immune system, and even produce chemicals that affect your mood. When your microbiome is healthy, you will feel great. But when you eat certain foods, you can accidentally "starve" the good bacteria and feed the bad bacteria that causes inflammation.

So, which foods should you limit to keep your gut happy? Here are the 7 worst foods for gut health and how they impact your body.

Number one is Ultra-processed foods

A list of ultraprocessed foods like donuts, crisps, burgers, popcorns etc

Ultra-processed foods are items like boxed snacks, frozen dinners, and sugary cereals. These aren't just "fast food" but they are industrial products filled with additives like emulsifiers.

Think of emulsifiers as a kind of "food glue" that keeps ingredients from separating. Unfortunately, research suggests they can act like detergent on your gut lining, wearing down the protective mucus layer. When this layer thins, it can lead to chronic inflammation and a higher risk of digestive issues.

Pro Tip: Check the back of the label for ingredients like carrageenan or polysorbate 80. If the list is long and full of words you can not pronounce, it’s likely ultra-processed.

Number two is added and refined sugars

An image showing various types of refined sugar

Sugary drinks, candies, and white breads might taste good, but they are a feast for the "bad" bacteria in your gut. These harmful microbes thrive on sugar, and when they overgrow, the feed on "good" bacteria leading to gut imbalance.

High sugar intake is also linked to a "leaky gut," where the lining of your intestines becomes more permeable, allowing toxins to slip into your bloodstream.

Number three is artificial sweeteners

An image showing artificial sugar 

Many people switch to "diet" sodas or "sugar-free" snacks to save calories. However, sweeteners like sucralose and saccharin might be doing more harm than good for your belly.

Studies show that these sweeteners can actually change the types of bacteria living in your gut. Even though they have zero calories, they can affect how your body processes real sugar, which may lead to higher blood sugar levels over time.

Number four are deep-fried foods

An image showing deep fried foods

Fried chicken and French fries are often cooked in highly processed vegetable oils at very high temperatures. These oils are rich in omega-6 fatty acids, which can be pro-inflammatory if you eat too much of them.

Deep-fried foods are also very hard to digest. Because they stay in your stomach longer, they can cause acid reflux and slow down your overall digestion, making your gut work overtime.

Number five is excessive alcohol

An image showing a glass of beer

Alcohol is a direct irritant to your digestive tract. It can cause an imbalance in your bacteria (known as dysbiosis) and damage the "tight junctions" that hold your gut lining together.

When these junctions fail, you end up with increased intestinal permeability, (a leaky gut). This can cause your immune system to go into overdrive, leading to brain fog, fatigue, and skin issues.

Pro Tip: If you choose to drink, stick to the "one-for-one" rule: have one full glass of water for every alcoholic beverage to help flush your system and stay hydrated.

Number six are processed meats

An image showing sausages, diced meats etc

Deli meats, bacon, and sausages are often high in salt and contain preservatives called nitrates. These chemicals have been linked to inflammation and even an increased risk of colon cancer.

Processed meats are also usually very low in fiber. Since fiber is the main "food" for your healthy gut bacteria, eating too much meat and not enough plants can essentially starve your microbiome.

You might be interested in; How Fiber Balances Hormones Naturally!

Number 7 on the list is refined grains

An image showing a split image between whole grains and refined grains

White bread, white pasta, and white rice have had the fiber-rich "husk" stripped away. Without that fiber, these grains turn into sugar very quickly in your body.

Fiber acts like a broom for your digestive tract, keeping things moving. When you eat a diet full of "beige" refined grains, you miss out on the prebiotics, the special fibers that feed your beneficial bacteria.

Pro Tip: Try the "30-a-week" challenge. Aim to eat 30 different types of plant foods (fruits, veggies, nuts, seeds, and spices) every week to maximize the diversity of your gut bacteria.

Bonus Pro Tip is to use "The Addition Rule"

An image showing a healthy plate containing carbs, protein, vegetables

Most diets fail because they focus on what you can not have, which often leads to cravings and "food guilt." Instead, try a technique called The Addition Rule.

Instead of telling yourself, "I can’t have chips," tell yourself, "I am going to add a small side salad or some sliced cucumbers to this meal first."

By focusing on adding high-fiber, nutrient-dense foods to your plate, you naturally "crowd out" the less-healthy options. Your stomach fills up on the good stuff giving your gut bacteria the fiber they crave and leaving you feeling satisfied before you even get to the processed snacks. It’s a simple mindset shift that turns healthy eating from a chore into a win.

A Table Summary 

↔ Swipe to see full table

The Food	Why It’s Tough	The "Addition Rule" Swap
Ultra-Processed Foods	Emulsifiers wear down your gut's protective mucus layer.	Add: Fresh berries or carrot sticks to your snack.
Added Sugars	Feeds "bad" bacteria and yeast, causing bloating.	Add: Fiber-rich apple slices with nut butter.
Artificial Sweeteners	Can reduce bacterial diversity and impact blood sugar.	Add: Infused water with fresh mint and cucumber.
Deep-Fried Foods	High in inflammatory oils and hard to digest.	Add: A large side of steamed greens to aid digestion.
Excessive Alcohol	Damages "tight junctions" causing a leaky gut.	Add: A full glass of water between every drink.
Processed Meats	High in nitrates; linked to gut inflammation.	Add: Beans or lentils to your meal for extra fiber.
Refined Grains	Lacks the fiber your "good" bacteria need to survive.	Add: One tablespoon of chia or flax seeds to your bowl.

The Bottom Line

Your gut health isn't about being perfect; it's about balance. You don't have to cut these foods out forever, but reducing how often you eat them can make a huge difference in how you feel. By swapping processed snacks for whole foods and sugary drinks for water or herbal tea, you’re giving your "second brain" the fuel it needs to thrive.

Ready to give your gut a fresh start? Try swapping your morning sugary cereal for oatmeal with berries tomorrow, and your microbiome will thank you!

READ NEXT: WHAT ARE THE 3 F's FOR GUT HEALTH

Disclaimer: The information in this article is for educational purposes only and is not intended to replace professional medical advice. Always consult with a healthcare professional or registered dietitian before making significant changes to your diet, especially if you have an underlying health condition.

References

Ganesan, R., et al. (2025). Microbiome-derived metabolic functions in liver diseases. Frontiers in Cellular and Infection Microbiology.

Jarmakiewicz-Czaja, S., et al. (2025). Effects of food additives on the gut microbiome. Medicina.

MDPI (2025). Ultra-processed foods and inflammatory bowel disease. Nutrients.

MDPI (2026). Gut microbiota in IBD: The effects of diet. Nutrients.

Research Protocols (2025). Effects of sweeteners on gut microbiota. JMIR Research Protocols.

Shukla, S., & Hsu, C. L. (2025). Alcohol and the gut–brain axis. Microorganisms.

Trumbo, P. R., et al. (2024). Science-based classification of processed foods. Frontiers in Nutrition.