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.
Many fast food meals have added sugar. That means extra calories without added nutrition.
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 Trusted Source of sodium per day. More than 70%Trusted Source of sodium comes from processed foods and restaurant meals.
Effect on the respiratory system
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.
Effect on the central nervous system
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.
Effect on the reproductive system
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.
