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.

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Among the macronutrients — carbs, fat, and protein — fat is the most slowly digested (1).

Because greasy foods contain high amounts of fat, they slow stomach emptying. In turn, food spends more time in your stomach, which can cause bloating, nausea, and stomach pain (2).

In people with digestive complaints, such as irritable bowel syndrome (IBS), chronic pancreatitis, or a stomach bug, high levels of fatty foods may trigger stomach pain, cramping, and diarrhea (1).


Greasy meals delay stomach emptying and may cause bloating, nausea, and stomach pain. In people with certain digestive conditions, these foods may worsen symptoms like cramping and diarrhea.

Greasy foods are known to harm the healthy bacteria that live in your gut.

This collection of microorganisms, also called the gut microbiome, affects the following:

  • Digestion of fiber. Bacteria in your gut break down fiber to produce short-chain fatty acids (SCFAs), which have anti-inflammatory effects and may protect against digestive disorders (3).
  • Immune response. The gut microbiome communicates with immune cells to help control your body’s response to infections (4, 5).
  • Weight regulation. An imbalance of gut bacteria may contribute to weight gain (6, 7).
  • Gut health. Disturbances of the gut microbiome are linked to the development of IBS, while probiotics — live, healthy microorganisms found in certain foods — may help improve symptoms (8, 9, 10).
  • Heart health. Healthy gut bacteria may help boost heart-protective HDL (good) cholesterol, while harmful species may produce artery-damaging compounds that contribute to heart disease (11, 12).

A high fat diet, such as one rich in greasy foods, may damage your gut microbiome by increasing the number of unhealthy gut bacteria and decreasing the number of healthy ones (13).

These changes may be associated with obesity and other chronic illnesses, such as cancer, heart disease, diabetes, and Parkinson’s disease (13).

All the same, further research on diet and gut health is needed.


Unhealthy, greasy foods can disturb the balance of bacteria in your gut, allowing unhealthy strains to grow. This is linked to weight gain and numerous chronic diseases.

Greasy foods, which are cooked in large amounts of fat, may cause weight gain due to their high calorie count.

For example, a small baked potato (3.5 ounces or 100 grams) contains 93 calories and 0.1 grams of fat, while the same amount of french fries packs 312 calories and 15 grams of fat (14, 15).

Observational studies link a high intake of fried and fast foods to increased rates of weight gain and obesity (16, 17, 18).

Obesity is associated with many negative health conditions, including heart disease, diabetes, stroke, and certain cancers (19, 20).

In particular, a high intake of trans fat may cause weight gain.

Trans fats are formed when vegetable oils are chemically altered to stay solid at room temperature. Despite regulations on their use, they’re still found in many greasy foods due to the use of partially hydrogenated vegetable oils in frying and food processing.

Animal studies note that trans fats may lead to small increases in weight — even without excess calorie intake (21, 22).

Additionally, an 8-year study in 41,518 women determined that those were overweight gained an additional 2.3 pounds (1 kg) for every 1% increase in their trans fat intake (23).

Although other studies haven’t backed up this finding, regularly eating greasy foods is likely to interfere with weight control (24).


Greasy foods are high in calories, excess fats, and trans fats, all of which can lead to weight gain and obesity.

Greasy foods have several negative effects on heart health.

For example, fried foods have been shown to increase blood pressure, lower HDL (good) cholesterol, and lead to weight gain and obesity, all of which are associated with heart disease (17, 25, 26).

For example, research reveals that potato chips increase inflammation and may contribute to heart disease (27).

Furthermore, your risk of heart disease may be linked to how frequently you eat fried foods (28).

One study found that women who ate 1 or more servings of fried fish per week had a 48% higher risk of heart failure than those who ate just 1–3 servings per month (29).

In another study, people who ate 2 or more servings of fried fish per week had a 63% higher risk of heart attack or stroke than those who ate 1 or fewer servings per month (30).

Additionally, a large observational study in 6,000 people across 22 countries associated eating fried foods, pizza, and salty snacks with a 16% increased risk of stroke (31).


Greasy foods may increase your risk of heart disease and stroke due to their effects on weight, blood pressure, and cholesterol.

Greasy foods may increase your risk of type 2 diabetes (32).

Consuming fast food, which includes not only greasy foods but also sugary drinks, leads to high calorie intake, weight gain, poor blood sugar control, and increased inflammation (33).

In turn, these factors boost your risk of type 2 diabetes and metabolic syndrome — a group of conditions that includes obesity, high blood pressure, and high blood sugar (33).

For example, a large observational study found that eating fried foods 1–3 times per week increased the risk of type 2 diabetes by 15% — but 7 or more instances per week increased the risk by 55% (28).

Another study found that people who ate fast food more than two times per week had twice the chance of developing insulin resistance, which can be a precursor to diabetes, compared with those who ate them less than once per week (34).


Eating greasy foods may raise your risk of type 2 diabetes by increasing body weight and inflammation, as well as impairing your blood sugar control.

Many people link greasy foods to breakouts and acne.

In fact, studies associate the Western diet, which is rich in refined carbs, fast food, and greasy items, with acne (35, 36).

A study in over 5,000 Chinese teenagers found that regularly eating fried foods increases the risk of acne by 17%. What’s more, another study in 2,300 Turkish teenagers revealed that eating greasy items like sausages and burgers increased acne risk by 24% (37, 38).

However, the exact mechanism behind this effect remains unclear.

Some researchers propose that poor diet can affect gene expression and alter hormone levels in a way that promotes acne (39, 40, 41, 42, 43).

Western diets with a high ratio of omega-6 to omega-3 fatty acids may likewise cause increased inflammation that leads to acne. While omega-3s occur in oily fish, algae, and nuts, omega-6s are found in vegetable oils, nuts, and seeds.

Oils used in frying greasy foods are high in omega-6s and thus may contribute to an imbalance in this ratio (42, 44, 45).

Some greasy foods, like fried doughnuts, are also high in refined carbs. These are sugars and refined grains that are stripped of their fiber and many nutrients.

Because sugary foods increase the activity of certain hormones in your body — including androgens and insulin-like growth factor 1 (IGF-1) — they may promote acne by raising your production of skin cells and natural skin oils (40, 46).

Keep in mind that more research on acne’s causes is needed (47).


Greasy foods may contribute to acne by increasing inflammation and altering gene expression and hormone levels.

A diet rich in greasy, fatty foods may cause problems with brain function.

The weight gain, high blood pressure, and metabolic syndrome linked to greasy foods are also associated with damage to your brain’s structure, tissues, and activity (48, 49, 50).

Two large studies in 5,083 and 18,080 people, respectively, tied diets high in greasy and fried foods to a decline in learning ability and memory, as well as an increase in inflammation (51, 52).

Additionally, diets high in trans fats have been linked to impairments in brain function.

One study in 1,018 adults associated each gram of trans fat eaten per day with worse word recall, indicating memory harm (53).

Furthermore, in a study in 38 women, a higher intake of saturated and trans fats was correlated with poorer word recall and recognition, in addition to poorer performance in spatial tasks (54).

Finally, a review of 12 studies linked trans and saturated fat to dementia risk, although some results were conflicting (55).

Overall, more research is necessary.


Greasy foods may harm your learning and memory, as well as increase your risk of dementia. Yet, further studies are needed.

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 little or no oil. This technique works particularly well with potatoes as an alternative to french fries.
  • 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.

Oven frying, air frying, steaming, and grilling are all great alternatives to traditional, oil-heavy frying. Additionally, many popular greasy foods are easy to replace with whole, nutritious options.

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.