Your body on fast food: 13 Harmful effects of eating fast food
08/22/2020 / By Joanne Washburn / Comments
Your body on fast food: 13 Harmful effects of eating fast food

You might want to think twice before sitting down to that single fast-food meal. Fast food does no good for our bodies, both on the inside and outside.

Foods like potato chips, soda, french fries, ice cream and candies might be cheap and accessible; however, these foods are teeming with calories, fats, sugar, sodium and cholesterol, all of which can harm our bodies in excess.

Harmful effects of fast food

It’s no secret that a bad diet and poor eating habits can lead to several health problems, from constipation to diabetes.

Frequent consumption of fast foods qualifies as poor eating habits, and a diet comprised of fast-food take-outs and processed foods is far from being considered a good one.

Take a look at some of the short- and long-term effects of eating fast food on the regular, according to dietitians:

Nutritional deficiencies

Despite their high-calorie content, fast foods offer little nutrition. In the long run, snacking on fast foods too often can increase our risk of nutritional deficiencies. Being deficient in certain nutrients are associated with a wide range of health problems.

Processed foods, for instance, contain little fiber. But our bodies require copious amounts of this essential macronutrient to maintain good gut health and to control blood sugar. On the other hand, insufficient intake of iron, another important mineral missing in fast food, can lead to anemia, a common blood disorder.


The packaging that fast foods sit in could also pose certain health risks. In 2018, American researchers found that people who ate fast foods more often had 35 percent higher levels of phthalates than those who prepared food at home.

Phthalates are endocrine-disrupting toxins used to line the plastic packaging of processed foods and drinks. These toxins are also associated with inflammation and chronic conditions like heart disease and diabetes.


Consumption of excess fast food can confuse our brains When we eat fast food, our brain receives mixed signals that make it difficult to determine whether it needs food or not. This makes it easier to overeat, indulge cravings or snack in between meals.

But although putting on a couple of pounds might not seem like a big deal at first glance, those extra pounds could be harming the heart, forcing it to pump blood double-time. Obese individuals also tend to have higher levels of bad cholesterol in the bloodstream, which can aggregate into plaque along the arteries.

In the end, all of these lead to a greater risk of heart disease and its complications, including heart attack, heart failure and stroke. Also, being obese puts a strain on other vital organs like the liver, the lungs and the brain.


Like heart disease, diabetes is one of the more serious side effects of eating too much fast food. Foods teeming with sugar like ice cream, candies, sodas, pastries and desserts can lead to an increase in blood glucose.

If blood glucose levels are too high, the pancreas will produce more insulin, the hormone responsible for controlling blood sugar. Over time, cells will become resistant to this hormone. This could then progress to diabetes if left untreated.


In 2008, American researchers found that fast food grilled chicken contained a chemical that, when heated, is associated with cancers of the breast, prostate and colon.

Fast-food meats are also loaded with additives like sodium nitrate and sodium nitrite to enhance their natural color and to kill bacteria. However, these additives can break down into substances that can cause cancer.

Weaker bones

Brittle bones prone to fractures could also be the result of a fast-food diet. Sodium, a nutrient abundant in fast foods like hamburgers and french fries, can weaken bones. This, coupled with the insufficient intake of bone-building nutrients like vitamin D and calcium, can heighten the risk of osteoporosis in later life.


Our bodies require a certain amount of calories to power important processes. The right amount would depend on our weight and age group, so consuming large doses of calories in one sitting isn’t often a good idea. Plus, the calories from nutrient-poor foods like fast foods do little for our bodies.

Instead, these calories fill up the stomach and signal to the brain to slow down and focus more on digesting the food. This, in turn, causes feelings of tiredness, sleepiness and fatigue.

Brain fog

Fast foods can trigger and promote inflammation in the brain, which can then affect vital cognitive functions like learning and concentration. Insufficient intake of good fats like omega-3s can also deprive the brain of the fuel it needs to power important processes.

Marisa Moore, a registered dietitian nutritionist, explains that saturated fats can have a negative impact on brain function. On top of their effects on heart health, these fats can also lead to poor focus, impaired learning and slower reflexes.

Poor mental health

The state of our mental health also depends on the foods we consume. For instance, eating fast foods high in bad fats can lead to depression.

In fact, Spanish scientists found a link between fast food and a greater risk of suffering from depression in 2012. Their research findings indicated that frequent consumers of fast food and commercial baked goods had a 51 percent higher risk of depression.

In addition, insufficient intake of omega-3s from fish, oils and nuts can create a more anxious mental state.

Bad skin

Breaking out? Fast food could also be the cause of that. In particular, simple sugars, white flour, and refined carbohydrates in fried foods like french fries can cause skin issues like acne, said Amy Shapiro, a registered dietitian and the founder of the private practice nutrition office Real Nutrition NYC.

But even if you don’t get acne, you can expect to see dull and lifeless skin since fast food lacks essential nutrients needed for maintaining good skin. These include vitamins A, C and E, as well as copper, zinc and selenium.


Copious amounts of sodium in fast foods are a recipe for bloating. Our bodies require little sodium to function, but it is often added to a lot of processed food products to enhance flavor or to extend shelf-life.

This extra sodium does nothing good for our bodies. Instead, it causes our bodies to retain more water than it flushes out, creating that bloated feeling.


Fast foods aren’t known for their high fiber content. Fiber has a huge role in keeping the digestive system in tip-top shape. It keeps stool from becoming too hard and difficult to pass, and it also feeds the good bacteria in the gut that protect it from infection and disease.

In 2019, Italian researchers found that junk foods and processed foods can also have a major impact on the occurrence of food allergies in children. The researchers suspect that this effect stems from the negative impact of the foods on the gut microbiome.

Bad teeth

Sugars from sodas, candies, desserts and processed pastries combine with saliva and bacteria present in the mouth to form plaque. If left unchecked, plaque can erode the enamel protecting the teeth and make them more susceptible to dental caries.

The short-term effects of eating fast food might not seem all that serious, but fast food can cause irreparable damage to our bodies if it continues to make up the bulk of our diet in the long run. Don’t wait for that to happen. Cut back on fast food now and switch to healthier, nutrient-rich foods.


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