We all like a bit of junk food every now and again. Eaten in moderation, a chocolate bar, burger, or a bag of chips can be a nice little occasional treat. But too much junk food can really harm you, leading to all sorts of health complications as you grow older.

What is junk food?

Junk food is unhealthy and high in calories from sugar or fats. It also has very little nutritional value, being low in vitamins, minerals, and dietary fiber. Junk food tends to be highly processed, and the term HFSS (high in fat, salt, and sugar) food is synonymous with it. The term has been pejoratively used since at least the 1950s, which shows just how long we have realised its harmful influence on our diets.

The concerns about junk food's negative effects on health have led to several public health awareness campaigns in recent years. Many countries have placed restrictions on the advertising and sale of junk foods, especially to children. This is for good reason too - scientists and activists are finding that the harm caused by junk food stretches far beyond just mere weight gain.

Junk food can contribute to obesity and other chronic health conditions.

When eaten very often, junk food contributes toward an increased risk obesity, cardiovascular disease, and other chronic health conditions. This is due to the excess levels of fat, simple carbohydrates, and processed sugars found in junk food.

Several studies have been performed which have suggested a direct correlation between junk food consumption and increased risk. As early as the age of 30, arterial clogging, which lays the groundwork for future cardiovascular disease, can start to occur due to excessive junk food consumption (researchgate.net/publication/257536304_Effects_of_junk_food_and_beverages_on_adolescents_health_A_review_article).

Higher levels of sugar and other unhealthy elements of junk food also leads to increased diabetic risk in people who eat too much of it, as they cannot regulate their blood glucose effectively.

Junk food can lead to reduced consumption of other, healthier foods.

The ideal diet consists of a mixture of different foods which give us nutritional benefits. However, if we consume junk food regularly, we eat less nutritious food. For example, if we're snacking on chips and candy, we eat less fruit and vegetables. If we're drinking sugar-laden soda, we're drinking less milk or orange juice.

Junk food can be addictive.

In recent years, there has been growing evidence that junk food can actually be addictive. A 2010 study by the Scripps Research Institute (ncbi.nlm.nih.gov/pmc/articles/PMC2947358/) suggested that junk food consumption has the same kind of brain activity altering affect that addictive drugs like cocaine and heroin have.

The study gave rats unlimited access to junk food for several weeks and found that the pleasure centers of their brains became desensitized, meaning that they required more food to gain the same amount of pleasure. When the junk food was taken away from them and replaced with a healthy diet, they starved for two weeks instead of eating the healthier food.

Junk food can lead to overeating.

Junk foods have a lower satiation value, meaning that we require more to fill us up. This leads to overeating, which in turn leads to weight gain and over-reliance on food which provides negligible nutritional benefits.

Eating junk food may contribute to depression.

Eating junk food may increase the risk of depression. A study (theguardian.com/society/2018/sep/26/eating-junk-food-raises-risk-of-depression-says-multi-country-study) by researchers from Britain, Australia, and Spain examined 41 previous studies on the links between depression and diet and found that there was a potentially causal effect of junk food upon this common mental health issue.

One way in which junk food may have this effect is that it causes chronic, systemic inflammation if consumed in excess. Chronic inflammation carries pro-inflammatory molecules into the brain and can negatively impact neurotransmitters, which are responsible for mood regulation.

Junk food - the lowdown.

Junk food is incredibly unhealthy. Just eating it once a day can contribute to elevated risks associated with several health conditions, so it should be consumed in moderation. A "Mediterranean" diet, high in unsaturated oils, vegetables, pulses, grains, fruits, legumes, fish, and cereals is widely considered to be the most balanced diet, but there are many healthier options than over-consumption of chips, chocolate, soda, or fast food. Junk food may be cheap, convenient, and readily available, but what is it doing to you?