Processed and junk foods: Bad news for pretty much every system in the body

By Liz Meszaros, MDLinx
Published October 24, 2018

Key Takeaways

The number of fast foods restaurants in American has doubled since 1970. Is it a coincidence that since that year, the number of obese Americans has more than doubled as well? Likely not, when you consider that nearly 50% of American adults eat fast food at least once a week.

Fast foods—foods that are prepared and eaten quickly—are categorized as processed or junk foods.

But what are processed foods? Any food that has been chemically processed and made only from refined ingredients and artificial substances is a processed food. And the terms “processed food” and “junk food,” for all intents and purposes, are interchangeable.

Here’s a look at the basic characteristics of processed/junk foods:

  • Usually full of added sugar and high-fructose corn syrup, and the largest source of added sugar in the diet. Aside from empty calories, sugar has been linked with insulin resistance, high triglycerides, cholesterol, and increased fat accumulation in the liver and abdominal cavity. Sugar consumption also has a strong association with heart disease, diabetes, obesity, and certain types of cancer.
  • Designed for overconsumption. These foods are specifically engineered to be especially rewarding to the brain, which can lead to overconsumption.
  • Contain artificial ingredients. Manufacturers use artificial chemicals in these foods for various reasons, which include preservatives, colorants, flavorants, and texturants.
  • Can become addicting because they are designed to be “hyper-rewarding.” In fact, the ingredients in processed/junk food can wreak havoc on the brain’s biochemistry due to the intense dopamine release that occurs in some people after consumption.
  • Often high in refined or simple carbohydrates. These carbohydrates are quickly broken down, and lead to rapid blood sugar and insulin spikes. These in turn can lead to carbohydrate cravings just hours later, when blood sugar levels return to normal.
  • Low in nutrients compared with whole, unprocessed foods. A diet high in processed foods can lead to a lack of vitamins, minerals, antioxidants, and other trace nutrients found in whole foods.
  • Low in fiber. Processed/junk food is typically very low in fiber because it’s either lost or intentionally removed during processing. Soluble, fermentable fiber found in whole foods has various important health benefits.
  • Require less time and energy to digest. Processed foods are easier to chew and swallow, also contributing to overconsumption. More can be eaten in a shorter amount of time resulting in more calories in while less energy is burned (fewer calories out).
  • High in trans fats. The refined vegetable and seed oils used to make processed foods are often hydrogenated, and become trans fats, which have high amounts of omega-6 fatty acids, which in turn cause oxidation and inflammation in the body.


Effects on the body

Processed/junk foods can cause a plethora of problems throughout the body. Most recently, researchers of the NutriNet-Santé study found that every 10% increase in the proportion of ultra-processed foods consumed corresponded with a 12% higher risk of cancer.

Additional effects on different body systems include:

  • Digestive system: As processed/junk foods are broken down, carbohydrates are released as glucose into the bloodstream, increasing serum glucose levels. The pancreas responds by releasing insulin. Frequent and continuous spikes in blood sugar, and the ensuing spikes in insulin to deal with them, may increase the risk for insulin resistance, type 2 diabetes, and weight gain.
  • Respiratory system: Extra calories from processed/junk food can cause weight gain and obesity. This extra weight can put pressure on your lungs and heart, and cause difficulty breathing. In one study, researchers found that asthma was more likely in children who ate fast food at least three times per week. Further, Australian researchers found that, in non-obese asthmatics, a single fast-food meal high in saturated fat increased airway inflammation and the potential for an asthma attack.
  • Central nervous system: Researchers in Spain found that, in the long-term, people who ate processed/junk foods were 51% more likely to develop depression than those who didn’t or those who ate them infrequently.
  • Reproductive system: Processed/junk food contains phthalates, which can disrupt the hormones in the body. High phthalate levels have been shown to lead to reproductive problems, including birth defects.
  • Endocrine and cardiovascular systems: In a review of studies on junk food and heart health, researchers found that eating fast food more than once per week was associated with a higher risk of obesity, and eating it more than twice per week with higher risks of metabolic syndrome, type 2 diabetes, and death from coronary heart disease.
  • Integumentary system: Carbohydrates may affect the appearance of the skin, with carbohydrate-rich foods leading to spikes in the blood sugar, triggering acne. In addition, children/adolescents who eat fast food at least three times per week are more likely to develop eczema, according to results from the International Study of Asthma and Allergies in Childhood Phase Three.
  • Skeletal system: Bone density and muscle mass can be adversely affected by obesity, which can be caused by eating too many processed/junk foods. In addition, the carbohydrates and sugars in these foods can increase the acids in the mouth, which can cause a breakdown of tooth enamel and lead to cavities.


Another form of addiction?

In addition to physical effects, eating processed/junk food can cause serious psychological effects. Consumption of these foods causes the brain to release dopamine. When done repeatedly and chronically, the dopamine receptors will start to down-regulate. In the presence of high amounts of dopamine, the brain removes dopamine receptors for balance. But, with fewer receptors, more dopamine is required to reach them. This is known as “tolerance,” and is a tell-tale sign of addiction. Fewer dopamine receptors and less dopamine activity leads to feelings of unhappiness and the need to get a “fix.” This is known as “withdrawal,” another hallmark of addiction.

Previous research has shown that rats can become physically addicted to sugar in the same way that they can become addicted to abusive drugs. Neuroscientists from New York University, New York, NY, have found that cravings for unhealthy snacks have nothing to do with hunger, and suggest that these cravings are an addiction.

It follows that if individuals can develop a tolerance to, and have cravings for processed/junk food, withdrawal from not eating these foods is also possible.

In a recent study, researchers from the University of Michigan, Ann Arbor, MI, found exactly that—food addiction to highly processed foods may trigger addictive-like symptoms in some, including withdrawal. They created a self-report tool to measure the physical and psychological withdrawal symptoms to study the addictive qualities of highly processed foods.

Then, 231 subjects used the tool to report what happened when they reduced the amount of highly processed foods they ate in the past year. Researchers led by Erica Schulte, a doctoral candidate in psychology, found that sadness, irritability, tiredness, and cravings in the subjects peaked in the first 2 to 5 days after they stopped eating junk foods, after which they tapered off. This time course is similar to that of drug withdrawal symptoms.

So, if you’re thinking about grabbing some fast food on your way home for dinner, please think again. Your health may depend on it!

Share with emailShare to FacebookShare to LinkedInShare to Twitter