Skip to content

Dangerous Side Effects of Eating Fast Food Every Day, According to Science

Whether it's breakfast, lunch, dinner, or a snack, eating fast food every day is risky for your health.

Not every fast-food menu item is a bad one. In fact, some chicken sandwiches, burgers, chicken nuggets, and more are decent sources of protein that aren't packed full of other added ingredients. But, like other indulgences, science proves that moderation is key.

Eating at McDonald's, Chick-fil-A, Taco Bell, or other fast-food chains—even just for one meal every day—can have serious health consequences. While the nutritional information can be found for most items right on the menu, chains have enticing ways of getting you to buy more by way of a (likely fried) side, adding on extra sandwich toppings, or even upgrading your meal for cheap. Falling for these gimmicks only adds to the calories, fat, sodium, carbs, cholesterol, and sugar you're eating.

Here are some specific side effects of eating fast food every single day that you may experience, even if you're simply ordering a soda at McDonald's or a Whopper from Burger King for lunch. Before we start, read up on the 25 Best Fast-Food Hacks for Weight Loss.


Your risk of high blood pressure goes up.

Doctor Checking Blood Pressure Of Male Patient

The American Heart Association says you may not even realize how much salt is in the foods you eat. And fast food contains a ton of it (among other things). The AHA recommends consuming no more than 2,300 milligrams of sodium per day. Burger King's Triple Whopper with Cheese has 1,470 milligrams, so having that for lunch or dinner leaves you less than 1,000 milligrams to work with for the rest of the day. And that's only the burger!

If you regularly go over your daily recommended amount of sodium, your risk of high blood pressure goes up, as does your risk of a heart attack or stroke. Studies have found that people who eat four or more servings of French fries a week have a 17% higher risk of developing high blood pressure.

Related:  28 Unhealthiest Fast Foods of 2020


You'll have an increased risk of a heart attack.

fast food in takeout containers

The sodium in fast food isn't the only thing that increases your risk of a heart attack. Burgers, chicken, pizza, and other foods from restaurant chains contain a lot of saturated fat (not to be confused with monounsaturated fats, or healthy fats, which are found in foods like avocados, peanut butter, nut, and olive oil).

Saturated fat increases the LDL cholesterol numbers and lines the walls of the arteries that can lead to a heart attack, according to Harvard Health.

"The explosion of fast-food restaurants has significantly increased the intake of fried foods, and people are now eating 1,000 times the amount of soybean oil compared with the early 1900s," according to a review published in the American Journal of Lifestyle Medicine in 2018. "Humans never ate 400 calories of oil a day the way people do in America, especially in the Southern states—which are known for the highest stroke and heart attack rates in the world."

The total amount of fat you should have in a day is between 44 and 78 grams, the Mayo Clinic says. Eating one (just one!) Monster Angus Thickburger from Carl's Jr. tips your fat amount over for the day (and then some) with 89 grams of fat.

For more on the burgers you shouldn't order, here are the Worst Fast Food Burgers of 2020.


You'll be deficient in some nutrients.

whole foods

A review of studies that focus on fast-food found that a diet "Fast food consumption and out-of-home eating behavior is a main risk factor for lower diet quality, higher calorie and fat intake, and lower micronutrients density of food."

While taking supplements can help, the best way to get nutrients out of what you eat is to consume whole, plant-based foods. Here's how to cook your food to get the most out of it.


Your chances of developing Type 2 diabetes will be higher.

fast food ice cream

The high sodium, fat, calorie, sugar, and carb amounts in fast food can also lead to an increased risk of Type 2 diabetes. Of course, other factors, like your age, family history, activity level, and blood pressure also play a role, but a diet high in trans and saturated fats increase the amount of triglycerides in your blood, which can up your risk of developing this type of diabetes. That's not all: The high levels of sugar in some fast-foods can also be harmful.

For instance, Dunkin's new Sugarplum Frozen Coffee with Cream sounds pretty delicious, but the 167(!) grams of sugar in a large goes well beyond the American Heart Association's limit of 36 grams per day. A tip from the American Diabetes Association about how to control the sugar, fat, and other unhealthy ingredients says to order the smallest option or to split it with someone.

Other fast-food menu items have hidden sugar, too. Here are the 14 Unhealthiest Restaurant Menu Items of 2020.


You'll have an increased risk of cancer.

Michael von Aichberger/Shutterstock

An ingredient often used in fast-food meat has been associated with breast, prostate, and colon cancers for over 10 years. A 2008 study revealed the link between the chemical PhIP and cancer, and a lawsuit was subsequently filed in 2009 involving Burger King. After that, the burger chain agreed to post warnings about PhIP in its California restaurants.

The World Cancer Research Fund and the American Institute for Cancer Research both recommend limiting the amount of fast and processed foods to help maintain a healthy weight. "Greater body fatness is a cause of many cancers," both institutions say. For more on this, here are 7 Amazing Things That Happen When You Give Up Fast Food.

To get other health tips delivered straight to your email inbox every day, sign up for our newsletter!

Amanda McDonald
Amanda has a master's degree in journalism from Northwestern University and a bachelor's degree in digital journalism from Loyola University Chicago. Read more about Amanda