Junk Food: What Is it and How Does it Affect Your Health?

Junk food triggers inflammation, one of the mechanisms underlying many chronic and complex diseases that claim millions of lives each year.
Junk Food: What Is it and How Does it Affect Your Health?
Saúl Sánchez

Written and verified by el nutricionista Saúl Sánchez.

Last update: 19 March, 2021

Junk food can be classified as items or food that have very few nutrients, if any, but do have a high caloric content. In addition, this type of product usually has a high concentration of substances or elements that favor inflammatory or oxidative processes, thus harming our health.

It should be noted that very often the categorization of junk food depends on the way it is prepared, not on the food itself. For example, a pizza cooked in a fast-food chain could be included within this concept. However, if it’s made at home, with fresh ingredients, then its categorization could change radically.

Junk food – high calories, low nutrients

One of the main drawbacks of junk food is its high calorie content. Consuming it on a regular basis increases the risk of unbalancing the energy levels in your body, and this could create a form of addiction to favor its intake, thus conditioning an increase in weight based on fat.

We have to take into account the evidence that indicates that obesity and excess weight increase the incidence of chronic and complex diseases.

As it weren’t enough, these foods hardly contain quality nutrients, such as proteins of high biological value or unsaturated lipids. These elements have been shown to contribute towards good health, in addition to maintaining functional lean mass.

Junk food is also full of carbohydrates. Furthermore, they aren’t complex carbohydrates, which have a moderate impact on blood glucose and pancreatic activity, but, rather, simple carbohydrates.

They’re known as sugars, which have the ability to dramatically raise blood glucose, triggering a high production of insulin to maintain homeostasis.

Junk food can promote weight gain.
In general, heavy consumption of junk food is associated with being sedentary and being overweight.

The inflammatory substances in these types of foods

In order to improve palatability, junk food includes high amounts of substances that give a good flavor, but whose effects on the body are not beneficial at all.

An example of these would be trans fats. These are created from the subjection of lipids to high temperatures, a process by which their spatial configuration varies, from a chemical point of view.

According to research published in the journal Progress in Lipid Research, these elements increase inflammatory cascades, which have a negative impact on health. A regular consumption of trans fatty acids is associated with an increased risk of developing chronic diseases, such as cardiovascular diseases.

At the same time, junk food has a lot of added simple sugars, as we have already discussed. These ingredients not only contribute to increasing levels of inflammation in the body, but also increase the incidence of metabolic pathologies, such as type 2 diabetes.

There is solid evidence of the effects of sugar consumption on people’s health. Its regular intake causes resistance to insulin in the medium term, which ends up generating an inefficiency in this hormone when it comes to modulating blood glucose levels.

Junk food additives

In addition to the substances already mentioned, there are other elements that junk food producers regularly use to improve the palatability of processed products. They can also help to increase its useful life. In this way, they remain unchanged for longer, which maximizes business profits.

These elements are additives, mostly products of chemical origin that are added to food for commercial purposes.

Most of them have been tested in laboratories and in large population studies, making them safe for health. However, there is a group of them that still generates controversy.

For example, nitrites are associated with an increased risk of developing cancer of the digestive tract. This is stated by a study published in Nutrients. These are commonly present in processed red meats, which is why their consumption is discouraged.

Sausages, for example, are a good source of this class of additives that aim to increase the shelf life of the product.

The case of artificial sweeteners

Another particular case of additives that could be harmful to health is that of artificial sweeteners. They are introduced into food as a substitute for simple sugars, in order to improve marketing campaigns.

They are marketed under the banner of healthy food, although the scientific community has many doubts about such claims.

Although some of them aren’t metabolized in the intestines – thus being excreted without suffering alterations – others generate an impact on the microbiota. Habitual consumption of these elements has been linked to an alteration of the profile of certain bacteria.

This can create digestive or metabolic dysfunctions in the medium term, thus conditioning a person’s overall health. However, more ambitious long-term studies are still necessary to confirm the effects that sweeteners have on the body.

Some sweeteners are likely to be associated with an increased risk of intestinal-type inflammatory dysfunctions.

Soft drinks as part of junk food

When we talk about junk food, we’re not only referring to ultra-processed foods, bakery products, pre-cooked frozen foods, and sweets, but also soft drinks.

These beverages have high numbers of additives and simple sugars in their composition. They’re capable of increasing the energy value of a person’s diet and inducing insulin resistance.

It should also be borne in mind that the fructose they contain is capable of causing liver damage when administered freely, through liquids. In fact, this is considered one of the major promoters of non-alcoholic fatty liver.

For this reason, we need to restrict its consumption on a regular basis. Not even the ones that advertise on their label that they don’t contain added sugar are a good option.

Something similar happens with alcohol, which is a toxic substance regardless of the dose consumed. For this reason, the less you consume it, the better.

What actually is junk food?

We have talked about its characteristics, but we’re now going to mention exactly which products can be included under the banner of junk food. First of all, we’ll highlight food from fast-food chains.

These have systematized methods of preparation that seek palatability and efficiency, but not nutritional value. They have sugars, additives, and trans fats. In addition, they’re usually cooked by frying or battering, often reusing the oil.

Finally, they’re accompanied by sauces that increase the energy value without providing quality nutrients.

We can also find sweets and pastries in junk food, both industrial and artisanal. In this case, the main ingredient is table sugar. In some cases, it’s replaced by fructose, syrup, or honey, but the effect is the same.

They are usually baked at high temperatures, which alters the spatial configuration of the fats and creates waste products through the reactions of carbohydrates.

We mustn’t forget that they also have refined flours and additives. Its impact on metabolic health is significant. As we’ve already mentioned, soft drinks are also in the junk food group, as is pre-cooked frozen food.

However, in the case of the latter, we need to highlight an exception, as there are certain types of frozen foods that aren’t harmful.

An example would be vegetables, which are precooked with water and then frozen to keep them for a longer time. However, frozen pizzas, nuggets, and lasagne are classed as junk food.

It is important to know how to reject junk food to improve nutritional status.
A fundamental pillar of a healthy diet is knowing how to reject junk food when it appears in excess.

How much can you consume in a week?

Experts defend the need for a variable diet. Within this flexibility, junk food can be introduced in a timely manner. By consuming it occasionally, there’s no problem. However, you shouldn’t let it become a regular feature in your life.

Many diet formulas state that 90-95% of our weekly meals would ideally consist of fresh, quality foods. This would leave a small margin for sweets or industrial ultra-processed food. In this way, you can enjoy its flavors while minimizing the risks they pose to health in the medium term.

We also have to take into account the individual context. A high consumption of sugars in an active person isn’t the same as in a sedentary person, for example.

In the first case, the sugars will be used as the main energy substrate. As a result, they won’t have a relevant impact on body composition, and this will reduce the incidence of several complex pathologies.

This doesn’t mean that an athlete has carte blanche to consume all the sweets they want. Apart from the energy balance, there are other mechanisms that must be controlled and safeguarded, such as blood glucose.

From the point of view of sports performance, it’s not a positive thing to increase the presence of sweet food or junk food in the diet, no matter how much physical activity is carried out.

Junk food, a health hazard

As you have seen, junk food is an obvious danger to health in the medium and long term. Unfortunately, it’s a major part of today’s society’s eating habits, and families resort to it all too often.

This is a public health problem, as, in the long term, it will increase the incidence of complex pathologies.

Education is essential in this regard. Fresh foods are always your best bet, as they’re less dense from an energetic point of view, and have a much higher nutrient content. Neither do they contain chemical substances that can harm the body in the medium term.

We’re not saying you should never eat junk food, or that you need to be too strict in what you allow yourself to eat. However, home-made food without any additives should always predominate in your eating habits.

If you have healthy life habits, then you can occasionally consume more unhealthy food in order to enjoy its flavor, and share it in a social context with friends and family.

  • Ortega FB, Lavie CJ, Blair SN. Obesity and Cardiovascular Disease. Circ Res. 2016 May 27;118(11):1752-70.
  • Abdelhamid AS, Brown TJ, Brainard JS, Biswas P, Thorpe GC, Moore HJ, Deane KH, AlAbdulghafoor FK, Summerbell CD, Worthington HV, Song F, Hooper L. Omega-3 fatty acids for the primary and secondary prevention of cardiovascular disease. Cochrane Database Syst Rev. 2018
  • Valenzuela CA, Baker EJ, Miles EA, Calder PC. Eighteen‑carbon trans fatty acids and inflammation in the context of atherosclerosis. Prog Lipid Res. 2019
  • Johnson RJ, Sánchez-Lozada LG, Andrews P, Lanaspa MA. Perspective: A Historical and Scientific Perspective of Sugar and Its Relation with Obesity and Diabetes. Adv Nutr. 2017 May 15;8(3):412-422.
  • Crowe W, Elliott CT, Green BD. A Review of the In Vivo Evidence Investigating the Role of Nitrite Exposure from Processed Meat Consumption in the Development of Colorectal Cancer. Nutrients. 2019 Nov 5;11(11):2673.
  • Lobach AR, Roberts A, Rowland IR. Assessing the in vivo data on low/no-calorie sweeteners and the gut microbiota. Food Chem Toxicol. 2019 Feb;124:385-399

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