Fast Food's Effects on 8 Areas of the Body (2024)

Fast food is a common meal option, but it’s high in calories and low in nutrients. Eating too much of it could affect nearly all parts of your body.

Swinging through the drive-thru or hopping into your favorite fast food restaurant may happen more often than some of us would like to admit.

Between 2013 and 2016, 36.6% of U.S. adults ate fast food on a given day. The amount was nearly the same for children and adolescents, with 36.3% of them eating fast food on a given day during 2015 to 2018.

While an occasional fast food meal won’t hurt, a habit of eating out could be doing a number on your health. Read on to learn the effects of fast food on your body.

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Most fast food, including drinks and sides, are loaded with carbohydrates with little to no fiber.

When your digestive system breaks down these foods, the carbs are released as glucose (sugar) into your bloodstream. As a result, your blood sugar increases.

Your pancreas responds to the surge in glucose by releasing insulin. Insulin transports sugar throughout your body to cells that need it for energy. As your body uses or stores the sugar, your blood sugar returns to normal.

This blood sugar process is highly regulated by your body. As long as you’re healthy, your organs can usually handle these sugar spikes.

But frequently eating high amounts of carbs can lead to repeated spikes in your blood sugar.

Over time, these insulin spikes may cause your body’s normal insulin response to falter. This increases your risk of insulin resistance, type 2 diabetes, and weight gain.

»MORE:Living with diabetes? Explore our top resources.

Sugar and fat

Many fast food meals have added sugar. That means extra calories without added nutrition. The American Heart Association, which referred to people as either men or women, suggests only eating about 100 calories or 6 teaspoons of added sugar per day for women or 150 calories or 9 teaspoons for men.

Many fast food drinks alone contain more than the daily recommended amount of sugar. A 12-ounce can of Coca-Cola contains 9.75 teaspoons of sugar. That equals 140 calories, 39 grams of sugar, and no other nutrients.

Another common fast food ingredient, trans fat, is manufactured fat created during food processing. It’s commonly found in:

  • fried pies
  • pastries
  • pizza dough
  • crackers
  • cookies

No amount of trans fat is good or healthy. Eating foods that contain it can increase your LDL (bad cholesterol), lower your HDL (good cholesterol), and increase your risk of type 2 diabetes and heart disease.

Sodium

The combination of fat, sugar, and lots of sodium (salt) can make fast food tastier to some people. But diets high in sodium can lead to water retention, which is why you may feel puffy, bloated, or swollen after eating fast food.

A diet high in sodium is also dangerous for people with blood pressure conditions. Sodium can elevate blood pressure and put stress on your heart and cardiovascular system.

One study found that about 90% of adults underestimated how much sodium was in their fast food meals.

The study surveyed 993 adults and found that their guesses were lower than the actual sodium content by more than 1,000 mg.

Keep in mind that the Food and Drug Administration (FDA) recommends adults eat no more than 2,300 milligrams of sodium per day. More than 70% of sodium comes from processed foods and restaurant meals.

Excess calories from fast food meals can cause weight gain. This may lead toward obesity.

Obesity increases your risk of respiratory problems, including asthma and shortness of breath.

The extra pounds can put pressure on your heart and lungs, and symptoms may show up even with little exertion. You may notice difficulty breathing when you’re walking, climbing stairs, or exercising.

Restaurants may increase the challenge of calorie counting. Research indicates that people often inaccurately estimate the number of calories of menu items.

Your central nervous system consists of your brain and spinal cord. These areas of your body may also see an impact from eating fast food.

One study from 2020 found that among college students, eating higher amounts of fast food (and, interestingly, salad) was linked to a lower short-term memory score.

Still, other research from 2019 found no effect of fast food consumption on cognitive function. More studies are needed in this area.

The ingredients in junk food and fast food may have an impact on your fertility.

One study found that processed food contains phthalates. Phthalates are chemicals that can interrupt how hormones act in your body. Exposure to high levels of these chemicals could lead to reproductive issues, including developmental issues for a fetus.

The foods you eat may impact your skin’s appearance.

A research review from 2021 found that dairy, chocolate, foods high in fat, and foods with a high glycemic index (carbohydrates and sugar) were associated with acne, though more studies need to be done. These foods are often present in fast food.

On the other hand, the research suggested that eating fruits, vegetables, and fatty acids (found in fish and olive oil) helped protect against acne.

Carbs and sugar in fast food and processed food can increase acids in your mouth. These acids can break down tooth enamel. As your tooth enamel disappears, bacteria can take hold, and cavities may develop.

Obesity can also lead to complications with your bone density and muscle mass. People with obesity may have lowered bone quality and a higher risk of breaking bones, especially among older adults.

It’s important to keep exercising to build muscles, which support your bones, and keep up a healthy diet to minimize bone loss.

Eating fast food may affect your mental health along with your physical health.

A 2020 study found that consuming fast foods with sugary drinks increased the chance of mental health issues in middle school students in China.

Research from 2018 also suggested that eating a Western diet high in red meat, takeout, and refined foods was linked to a higher body mass index (BMI) and inflammation in 14-year-old participants. This was then associated with depressive symptoms and mental health issues when they were 17 years old.

Today, more than two in five U.S. adults and around one in five children have obesity.

Offerings at fast food restaurants may be contributing. One study found that between 1986 and 2016, portion sizes and the number of calories in restaurant entrées and desserts increased significantly.

As Americans eat out more frequently, it could have adverse effects for both individuals and America’s healthcare system.

What are the health risks of eating fast food?

Fast food is often high in calories, fat, and sugar but low in nutrients and fiber. While eating fast food occasionally isn’t a problem, consuming it frequently may raise your risk of obesity, heart attack, and other health issues.

What happens if you eat fast food more than two times a week?

Eating fast food too often may negatively affect your health. An older study from 2012 found that Chinese Singaporean adults who ate Western-style fast food at least twice per week had a higher risk of developing type 2 diabetes and dying from coronary heart disease compared with adults who consumed little or no fast food.

Fast food is a popular choice for its taste and convenience, but it tends to be high in calories, sugar, and fat and low in nutrients.

Eating fast food frequently may negatively affect multiple areas of your body, possibly increasing your risk of conditions including type 2 diabetes, obesity, and high blood pressure. As a result, it’s best for your health to eat it only occasionally.

Fast Food's Effects on 8 Areas of the Body (2024)

FAQs

How does fast food affect your body? ›

Excess calories from fast food meals can cause weight gain. This may lead toward obesity. Obesity increases your risk of respiratory problems, including asthma and shortness of breath. The extra pounds can put pressure on your heart and lungs, and symptoms may show up even with little exertion.

What body systems are affected when you eat too fast? ›

Consistently eating fast can have lasting effects on your overall health and well-being. Some of the short term effects include excessive bloating, elevated blood pressure, increased blood sugar levels and decreased nutrients to the body.

What are 2 effects of fast food has on the digestive system? ›

Discomfort to the Stomach and Kidney: As fast food contains various toxic elements, chemicals and high amount of sodium, these naturally increase the risks of developing bloating, stomach ulcers and sometimes even stomach cancer.

What are the effects of junk food on the body? ›

Long-term effects of junk foods

heart-related problems (such as cardiovascular disease, high blood pressure and cholesterol) overweight and obesity. osteoporosis. certain cancers.

What happens to your body when you fast from food? ›

The Science of Fasting

This helps drive blood sugar and insulin levels down, reducing your likelihood of gaining weight and developing diabetes or heart disease. Intermittent fasting also increases the release of human growth hormone, which regulates your metabolism and preserves muscle mass while burning fat.

What body systems does food affect? ›

Overview. The human body uses the process of digestion to break down food into a form that can be absorbed and used for fuel. The organs of the digestive system are the mouth, esophagus, stomach, pancreas, liver, gallbladder, small intestine, large intestine and anus.

Does eating fast affect your body? ›

Leisurely eating is better for your health, especially when it comes to digestion, weight and nutrition. When you eat too fast, you swallow more air, which can cause bloating and gas. Slowing down to properly chew your food helps to break down larger particles of food into smaller ones, aiding digestion.

How does fast food affect your brain? ›

When we eat junk foods the reward circuits within our brains activate and release the chemical dopamine. Our brains can become overwhelmed by the pleasure from these rewarding foods and in response, the brain adapts and makes more receptors for dopamine.

How to detox after eating junk food? ›

How to recover after binge eating
  1. Hydrate, hydrate, hydrate. ...
  2. Fill up on high-fiber, nutrient-rich foods and lean protein. ...
  3. Eat regular meals and snacks, and avoid going long hours without eating. ...
  4. Get active. ...
  5. Hit the sack. ...
  6. Give mindful eating a try. ...
  7. When to ask for help.
Feb 12, 2024

Does fast food affect gut health? ›

Junk food diets are often associated with a reduction in the diversity of the gut microbiome. This means that there are fewer different types of microorganisms in the gut, which can have a negative impact on overall health. Junk food consumption is linked to an increase in potentially harmful bacteria in the gut.

What are 5 major problems from eating fast food? ›

In the short term, fast food impacts blood sugar and blood pressure, increases inflammation, and may mean an individual does not eat enough necessary nutrients. In the long term, a diet rich in fast food could lead to issues with digestion, immunity, inflammation, heart health, obesity, and more.

What is the biggest disadvantage of fast food? ›

Understanding the Risks: Harmful Effects of Junk Food
  • High in Calories and Low in Nutrition:
  • Weight Gain and Obesity:
  • Increased Risk of Chronic Diseases:
  • Poor Digestive Health:
  • Negative Impact on Mental Health:
  • Increased Risk of Type 2 Diabetes:
  • Cardiovascular Health Concerns:
  • Dental Problems:

How does fast food affect your health and mood? ›

The gut-brain connection also plays a crucial role in mental health. Fast food diets, which are low in fiber and essential nutrients, can disrupt the balance of gut bacteria, affecting the production of neurotransmitters such as serotonin, which is a key player in regulating mood.

What happens to your body when you stop eating fast food? ›

Eating foods that are high on sugars, fats, calories and sodium lead to a higher risk of developing hypertension, heart diseases, diabetes, certain types of cancers, obesity, even asthma. If you stop consuming these foods, your overall health condition will definitely improve and you'll avoid these risks.

What are the side effects of eating processed foods? ›

While it may be convenient, consuming ultraprocessed foods on a regular basis increases a person's risk of health complications including cardiovascular disease, certain cancers, obesity and type 2 diabetes. But it can be hard to tell when these foods are on your plate.

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