We've all been there: starving, way past hangry, and convinced your stomach is starting to digest itself. And then you see it out of the corner of your eye, like a desert mirage: the unmistakable golden arches of a McDonald's. In a last ditch effort to save your sanity, you whip through the drive-thru and house a Big Mac and large fries faster than you can blink.


At the time, fast food seems like a true gift. It's freaking delicious, and it's cheap. But within a few hours, you may start to feel off. Your stomach may hurt, or you might notice your skin is a little greasier than usual. You immediately curse the meal you ravaged not too long ago. Here's what's actually going on in your body when you eat fast food.

You gain more weight

If you've ever looked at the nutrition facts on any food or drink label, you've probably noticed that every measurement is based on a 2,000 calorie diet. While the amount of calories you should eat daily to maintain a healthy weight depends on a number of factors, including your sex and height, in general the more calories you eat, the more weight you gain.

Fast food is notorious for containing a ton of calories. For example, a crunchy taco from Taco Bell has 190 calories, a Big Mac has 540 calories, and a Wendy's Baconator has 950 calories. Now, if these were your only meals of the day, that'd be one thing. But that's probably not the case, considering fast food is full of empty calories, meaning they hold little to no nutrients — which is why you're hungry again so soon after eating it. A 2004 study found that those who eat fast food frequently generally have a higher body mass index and are more likely to be overweight than those who don't.


You get tired

In 2015, a Daily Mail writer tested fast food's effect on the body by eating nothing but fast food for a full week. By the end of the week, she reported that her "concentration levels were much lower than usual and [her] fatigue was a real issue, even after a long night's sleep."

If you've ever had a food coma, you'll relate. It turns out the exhaustion you feel after eating a large meal is real. The sleepiness comes from a certain type of amino acid called tryptophan, which becomes more available to the brain via carbohydrates. Since fast foods are typically heavy in carbs, it makes sense that the more fast food you eat, the more tired you'll feel.

You raise your cholesterol levels

According to the American Heart Association, there are two types of trans fats: naturally-occurring, which comes from animals, and artificial, which are created industrially and are the types of trans fats most fast food companies use because they're inexpensive, last a long time, and — if we're honest — they make food taste damn good.

Trans fats are known to raise your cholesterol levels, which increases your risk of heart disease and stroke. In fact, they're so bad for you that some places have even restricted the use of them, the American Heart Association confirms.

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