This Is What Happens to Your Body When You Eat Fast Food a Lot

The Happy Meal may be one of the most paradoxically named products to ever hit the market.
Hand holding burger

Two weeks ago, a friend and I pulled into the drive-thru of a McDonald’s in Bennington, Vermont and indulged ourselves. We ordered a couple of value meals and a 10-piece nuggs for good measure. I estimated the meals to be around 1,400 calories each. We ate in near silence both staring through the windshield and off into the middle distance as if in a trance. As I finished off the remaining sweet and sour sauce, I resolved that I would put at least three months between this night and my next visit to the Golden Arches or indeed any other fast food establishment.


It wasn’t the sudden influx of calories alone that gave me pause, but a visceral and undeniable feeling that I was engaging in something like self-harm. When Super Size Me came out in 2004, it had very little effect on my fast food consumption. I was 27 then and seemingly indestructible. In the 14 years since then, the evidence linking regular fast food consumption with a litany of undesirable outcomes has become overwhelming. Here are just some of the ways that regular fast food consumption (say, a couple of times a week) is going to fuck with you if you let it.

Memory and cognitive function will decline

Every time I tuck into a meal at my favorite fast food joint, the condescending little voice in my head says something about how my decision-making processes are impaired. Well, that voice could be onto something. “It’s been long established that saturated fats can negatively impact the heart, but there’s also research that suggests high saturated fat intake may negatively impact brain function and memory,” says Atlanta-based nutritionist Marisa Moore.

Saturated fat is not necessarily the devil, but large amounts of it can create a dangerously unbalanced diet, especially if you’re supplementing it with sugar instead of good fats, carbs, and protein. One 2015 study from Oregon State University demonstrated that a diet high in both fat and sugar, caused changes in gut bacteria that appear related to a significant loss of "cognitive flexibility," or the power to adapt and adjust to changing situations.


You might increase your risk of depression

The Happy Meal may be one of the most paradoxically named products ever to hit the market. People who regularly consume fast food are 51 percent more likely to experience depression, and more likely to be single, work long hours, eat fewer fruits and veggies, and smoke, according to a 2012 study. And while talk therapy and meds are going to be your best options to battle depression, New York-based nutritionist Amy Shapiro tells me that nutrients such as B vitamins and Omega 3s have been associated (in some preliminary research) with lower instances of depression. These—as you can imagine—are not found in fast food items as abundantly, if at all.

You’ll up your chances of becoming obese

If you stray from a balanced diet of whole foods to one of fast food, the most obvious difference you’d register would be the enormous uptick in largely empty calories you’d consume at every meal. Within short order, this would begin to have a marked effect on your body composition and your overall health. “Fast food consists of high calorie foods that contain high amounts of carbohydrates and sugar with little to no fiber,” says Virginia Beach-based dietician Jim White. White explains that frequent consumption of these foods lead to insulin resistance, thus contributing greatly to weight gain. A recent study looked at the link between fast food and obesity and hypertension in children and painted an unsurprisingly grim picture.

You’ll also starve

Well, nutritionally speaking at least. See, the high calories in fast food are accompanied by low nutritional density. An excess of burgers and fries will mean a lack of the necessary nutrients it needs to function properly. “Your body is temporarily full with empty foods that don’t provide nourishment, so even though you may have eaten a lot of calories, you won’t be satisfied for long,” Shapiro says.

You could increase your chance of getting cancer

A study by the National Toxicology Program of the US Department of Health and Human Services says 2-methylimidazole causes cancer in lab rats. That’s bad because 2-methylimidazole is an ingredient in a caramel coloring which is used in most dark-colored sauces and sodas. It gets worse. Another of this coloring agent’s ingredients is 4-methylimidazole. Researchers tested the effects of 4-methylimidazole on rodents as well and concluded that there was “clear evidence of carcinogenic activity of 4-methylimidazole in male and female B6C3F mice.”


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Shapiro says that high smoke points and fried foods can contain carcinogens—a result of the heat of the cooking oil being too high or the charring of meats. “Possible pesticide use, antibiotics, and hormones found in poor quality meats may also be contributing to higher cancer rates,” she says, adding that without the intake of fruits and veggies which are high in antioxidants, fast food aficionados are missing nutritional help to offset the carcinogenic effect of their meals.

You’ll also be more at risk for heart disease

Fats commonly found in fast food are made up of saturated fatty acids. Those are fats that are solid at room temperature, often derived from animals and some plant oils. You’ll find it abundant in, say, a cheeseburger. Jim White warns that these fats can raise the blood cholesterol levels, which can lead to an increased risk of cardiovascular disease. It turns out that just living near where this food is available has a discernible effect on heart health. A Dutch study published in the European Journal of Preventive Cardiology that found that adults living within a half-mile of fast food outlets were more likely to develop heart disease than those living further away.

You’ll be constipated

Dietary fiber (commonly found in vegetables, fruits, whole grains, nuts, and seeds) plays a dominant role in the digestive system. Fiber helps keep your digestive tract working properly as it ushers wastes out of the body. It can help lower cholesterol and keep blood-sugar levels normal. “Unfortunately, most fast foods don’t contain high dietary fiber contents,” White says. Indeed, the National Institutes of Health calls out fast food as something to avoid should you need to get things moving.

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