Fast food is typically high in calories and lacks the nutritional value of whole foods. Evidence suggests that overeating commercial fast food products can negatively impact health in both the short- and long-term.

Many fast food establishments now list the number of calories in each item. However, this is only part of the consideration of whether a food is healthy or not.

Fast food is typically limited in terms of nutrition. It is often high in sugar, salt, saturated or trans fats, and many processed preservatives and ingredients. It can also lack some beneficial nutrients.

However, not all fast food has negative impacts, and a person can make an informed choice by researching the nutritional content of particular fast food items. People can find this information on the websites of most major restaurants.

Read on to learn the short- and long-term impact of fast food on health, and some tips for making healthier food choices.

The use of binary terms such as “male” and “female” or “men” and “women” in this article reflects the language of the sources we’ve used. Unless otherwise noted, it’s unclear whether the research we reference included participants with expansive gender identities.

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Fast food is typically high in sugar, salt, and saturated or trans fats. The Dietary Guidelines for Americans 2025 – 2030 suggests that overconsumption of these food components in ultra-processed foods is contributing to a health emergency.

Below are some short-term effects of fast food consumption.

Spike in blood sugar

Fast food breaks down quickly, causing a rapid spike in blood sugar because of the refined carbohydrates and added sugar. In turn, this causes a large insulin surge, resulting in a drop in blood sugar, which may cause people to feel tired.

Insulin promotes further hunger within a short time after the meal.

Blood pressure

According to a 2024 study, high consumption of ultra-processed foods, which can include fast food, is associated with a higher incidence of high blood pressure compared with eating fewer or unprocessed foods.

Increased inflammation

Research associates a frequent intake of fast foods with increased inflammation throughout the body. In particular, certain dietary components of fast food, such as added sugar, link with increased inflammation.

Research also links inflammation with various health conditions and complications, including:

Affects nutrient intake

Fast food does not typically contain fresh fruit and vegetables. If someone eats fast food frequently, they may find it challenging to reach their recommended daily intake of at least five servings of fruit and vegetables.

They may also have difficulties reaching their ideal fiber intake, which, according to the United Kingdom’s National Health Service (NHS), is 30 grams per day.

Binge eating

Fast food is highly palatable, meaning the body breaks it down quickly in the mouth, and it does not need much chewing. Therefore, it activates the reward centers in the brain rapidly.

This combination may train the palate to prefer these highly processed, highly stimulating foods and reduce someone’s desire for whole, fresh foods.

A 2024 review also highlights that some research highlights potentially addictive qualities of ultra-processed food items, such as fast food. Fast food and other types of ultra-processed food may also be more likely to trigger a cycle of binge eating or binge eating disorders.

Regularly or excessively eating fast food and other ultra-processed foods can harm a person’s health, contributing to diet-related chronic health conditions.

This is because most fast food is high in sugar, salt, saturated fat, trans fats, processed ingredients, and calories. It is also generally low in antioxidants, fiber, and other important nutrients.

Below are some ways fast food can impact health in the long term.

Digestive system

Many fast food meals are extremely low in fiber. Doctors associate low fiber diets with a higher risk of digestive conditions such as constipation and diverticular disease, as well as reductions in healthy gut bacteria.

Immunity and inflammation

A 2019 review examined the effects of a Western diet on a person’s immune system. This diet consists of high amounts of sugar, salt, and saturated fat from only a few sources.

The authors noted that a Western diet could lead to higher inflammation, lower control of infection, higher cancer rates, and a higher risk of allergic and autoinflammatory disease.

Memory and learning

A 2020 paper suggests a link between unbalanced diets high in saturated fat and simple carbohydrates, typical of fast food, and a lower capacity for memory and learning. Overweight or obesity due to this sort of diet may also raise the risk of Alzheimer’s disease.

Asthma

A 2021 study of 986 people from Qatar suggests there is a direct association between fast food intake or sweet dietary patterns and the incidence of asthma. More research is necessary to understand this link.

Heart disease

The Food and Drug Administration (FDA) suggests that a diet high in salt often increases a person’s blood pressure, making them more prone to health conditions such as stroke or heart disease.

The FDA also notes that a diet high in trans fats raises the amount of low-density lipoprotein or “bad” cholesterol and lowers the amount of high-density lipoprotein or “good” cholesterol, increasing the risk of heart disease.

Obesity

Fast food typically contains a high number of calories. If a person eats more calories than they burn each day, they gain weight, which may lead to obesity. Obesity can contribute to various health issues, including:

Education

Another consequence of younger people regularly eating fast food is a potentially unintentional lack of understanding of basic meal preparation, cooking, and healthy eating.

Over time, this perpetuates dependence on fast food, and people may not learn how to prepare healthy, balanced food in the home. Consuming healthy meals can support a person’s long-term health throughout their life.

Eating lots of fast food could also impact a person’s mental health and make them more prone to depression and anxiety.

A 2021 study found an association between healthy foods, such as leafy greens, nuts, and fish, and positive mood, while the opposite was true of fast food. In addition, women reported significantly more negative associations with fast food than men.

Eating fast food occasionally in moderation isn’t likely to cause lasting harm for your health. However, eating excessive amounts can contribute to the problems in this article.

Below are some tips for reducing your fast food intake:

  • If eating a fast food meal, opt for salad as a side instead of fries.
  • Try recreating fast food dishes, like burgers, at home with healthier ingredients.
  • Choose smaller portion sizes or save some of your food for another meal.
  • Prepare snacks and meals in advance to reduce reliance on fast food as the fastest or easiest option.
  • Plan your week’s meals in advance and buy everything you need ahead of time.
  • Work with a nutritionist or dietitian to create a healthier meal plan.

Fast food tends to be high in salt, sugar, saturated fats, trans fats, calories, and processed preservatives and ingredients. A wealth of well-conducted research has proven the negative health effects of consuming too much of these food components.

In the short term, fast food impacts blood sugar and blood pressure, increases inflammation, and may mean people do not eat enough necessary nutrients. In the long term, fast food may lead to issues with digestion, heart health, obesity, and more.

To preserve health, people can try to identify fast food items that contain less salt, fat, sugar, and total carbohydrates, and generally try to limit the amount of fast food they consume.