High in calories, fat, and salt, and low in healthy nutrients, greasy foods have both short- and long-term health effects. Diarrhea, weight gain, and acne are among them.

Greasy foods are not only found at fast food joints but also in workplaces, restaurants, schools, and even your home.

Most foods that are fried or cooked with excess oils are considered greasy. They include French fries, potato chips, deep-dish pizzas, onion rings, cheeseburgers, and doughnuts.

These items tend to be high in calories, fat, salt, and refined carbs but low in fiber, vitamins, and minerals.

While they can be an enjoyable treat on special occasions, greasy foods can negatively affect your body and health in both the short and long term.

Here are 7 effects of greasy foods on your body.

If you experience diarrhea or symptoms of indigestion (dyspepsia) like nausea, bloating, and uncomfortable “fullness” after eating greasy foods, how your gut handles greasy and fatty foods is likely to blame.

A review from 2023 explains that foods high in fat can slow down gastric emptying or how fast food moves from your stomach into the small intestine. While this can lead to feeling fuller at meal time, it can also contribute to an uncomfortable “heavy” feeling in your stomach after eating and symptoms of indigestion.

Fats, in general, take more time to digest compared to other nutrients because they requireTrusted Source pancreatic enzymes and bile from your liver. If you overwhelm your digestive tract with too much grease all at once, it can create a laxative effect that moves stool through your intestines before it has a chance to fully form (diarrhea).

Your gut microbiome is an ecosystem of microorganisms that help with everything from digestion to immune function. According to a review from 2022, diets that are high in fat and low in fiber may reduce the diversity of your gut microbiome and encourage the growth of pro-inflammatory bacteria over beneficial bacteria.

When your microbiome becomes less diverse with beneficial microbes, fewer microorganisms are available to aid in essential functions related to fat breakdown, regulation of inflammation, and protection against harmful pathogens.

Fats, of any kind, are higher in calories compared to carbohydrates and proteins. One gram of fat contains around 9 caloriesTrusted Source, compared to 4 calories per gram in carbohydrates and proteins.

High-fat diets can directly contribute to a caloric surplus, where you take in more energy than your body needs. When you have more calories than you need, your body stores them as fat deposits. Having a consistent caloric surplus can lead to weight gain and obesity.

Greasy foods can be sneaky sources of calories because the cooking method (like deep frying) adds fat calories to items that might be a protein or a carbohydrate at their base.

Most fried foods are fried in vegetable oils such as soybean, safflower, and sunflower oil. Some vegetable oils are high in omega-6 fatty acids. These fats may be harmful when consumed in excess, especially when not balanced with omega-3s, though more research is needed.

When oils high in polyunsaturated fats are heated to high temperatures for frying, they generate harmful lipid oxidation products that may contribute to oxidative stress and increased heart disease risk.

Additionally, a diet high in saturated fats may cause an imbalance in your LDL cholesterol and HDL cholesterol and can contribute to body-wide inflammation and the development of plaque in your arteries.

Greasy foods can affect your risk for diabetes by promoting weight gain, causing inflammation, and affecting cellular metabolism.

Obesity is a major risk factor for type 2 diabetes, and greasy foods can promote weight gain because they are often high in calories. Excess body fat in obesity can interfereTrusted Source with how well your cells respond to the hormone insulin, which is necessary for absorbing glucose from your bloodstream. Excess body fat can also get stored in your liver, which affects how well it processes glucose, further contributing to high blood sugar levels.

If you’ve noticed your skin breakouts after eating certain greasy foods, it might not always be the grease that’s to blame. According to the American Academy of Dermatology Association, certain greasy foods like donuts, fries, and potato chips are also high-glycemic foods, which means they cause a spike in your blood sugar after you eat them.

Blood sugar spikes can promote inflammation and sebum production in the skin, both factors that can contribute to the development of acne.

That doesn’t mean other greasy foods are off the hook when it comes to your skin. Research suggests saturated fats, on their own, may promote inflammation that could aggravate skin conditions.

Regularly eating greasy foods might affect your cognitive abilities. According to a 2024 review, foods high in saturated fats, like some greasy foods, affect central nervous system health by increasing:

  • dysbiosis (imbalanced gut microbiome)
  • intestinal barrier permeability
  • chronic, low-grade inflammation
  • oxidative stress
  • dysfunction in the blood-brain barrier

Your brain and your gut are connected by a two-way communication pathway called the gut-brain axis. This means changes in one can affect the function of the other. When your gut permeability increases from eating greasy foods, pro-inflammatory molecules and harmful pathogens can cross into your bloodstream and travel to the brain to cause neuroinflammation.

Neuroinflammation can affect how well your neurons communicate, and dysbiosis could lead to changes in the production of neurotransmitters necessary for central nervous system function.

There are multiple ways to reduce or avoid the intake of greasy foods. These include not only healthier cooking methods but also lifestyle choices.

Use healthier cooking methods

Greasy foods are often fried, which means that they’re cooked in a lot of oil. Methods that don’t use as much oil include:

  • Oven frying: This involves baking at a very high temperature (450°F or 232°C), which allows foods to get crispy using less oil than deep-frying.
  • Air frying: Air-frying machines circulate hot air around food, making it crispy on the outside but soft on the inside. It uses 70–80% less oil than traditional frying methods, meaning that your food won’t get greasy.
  • Steaming: This method uses the steam from hot water and requires no oil. It’s a great alternative when cooking foods like dumplings, fish, and vegetables.
  • Grilling: You don’t need too much oil for grilling. This technique is especially useful for meats and vegetables.

If you don’t want to forego frying entirely, be sure to use a skimmer to let the grease drip off and store the food on a paper towel to soak up the excess fat.

Replace greasy foods with healthier options

With minimal effort, you can replace fried foods with whole, nutritious options. Here are a few alternatives to common greasy foods:

  • Burgers. Instead of heading to the fast food joint, try making your own burgers at home with ground beef, lettuce, and whole grain buns.
  • Fries. Oven-baked potatoes are a great alternative to French fries. To vary it up, use other root vegetables like sweet potatoes, parsnips, and carrots.
  • Pizza. Instead of buying deep-dish varieties, try making Italian thin-crust pizza at home. You can use store-bought or homemade dough with healthy tomatoes, vegetables, and lean meats. Use cheese lightly to minimize the grease.
  • Potato chips. When you get a craving for salty fare, try crispy baked kale, lightly salted green beans, or wedges of baked tortillas or pita with hummus or edamame.
  • Fish and chips. Fish is incredibly healthy — but much less so when battered and fried. Good alternatives are pan-seared or baked fish with mashed potatoes, baked veggies, or salad.
  • Chinese takeout. Many Chinese takeaway dishes are greasy and fried. Instead of your regular options, try veggie-heavy stir-fries, steamed dumplings, and soups.
  • Fried chicken. Chicken can easily be baked or grilled instead of fried.
  • Doughnuts. If you’re wanting something sweet, try a smoothie, whole grain muffin with fruit or nuts, baked apple chips, or a piece of fruit.

Greasy foods like fries, chips, pizza, and doughnuts are high in calories and unhealthy fats.

A high intake of these foods can lead to weight gain, obesity, heart disease, diabetes, bloating, diarrhea, acne, and impaired brain function.

While it’s perfectly acceptable to enjoy fried foods on special occasions, you may want to limit your intake and choose healthier alternatives as part of a balanced diet.