Eating junk food is one of the worst things you can do to your body, and also to your mind,as there is a strong relationship between this type of food (high in saturated fats, refined flours and added sugars) and our mental health state.

Specifically, several studies have indicated that people who eat junk food regularly are often more likely to suffer from depression.

The higher glycemic index, the higher the risk of depression

A study conducted by Columbia University’s Department of Psychiatry wanted to find out whether foods with a high glycemic index were associated with higher chances of depression.

They analyzed data within the Women’s Health Initiative questionnaires, conducted to learn more about women’s health beyond menopause, a little-studied group. They used the information of some 70,000 women, none of them depressive at the beginning of the study.

The data showed that following a diet with a high glycemic index, including those rich in refined flours and added sugars, was associated with higher chances of depression. On the other hand, some aspects of the diet seemed to have the opposite effect, such as fiber, eating whole grains, fresh and whole fruits and vegetables or lactose, a type of sugar that comes from dairy and is placed in a low position within the glycemic index.

In this study it was not possible to determine the mechanisms by which this relationship occurs, but the authors suggested different possibilities: either that excessive consumption of refined sugars and starches is a risk factor for inflammatory and cardiovascular diseases, both related to the development of depression, or that this type of diet leads to the development of insulin resistance, which has been linked to cognitive defects similar to those found in people with higher depression.

More fast food, more depression

Another study, conducted in Spain, has also tried to deepen the relationship between junk food and depression. Performed by scientists from the University of Las Palmas de Gran Canaria concluded that people who often consume these foods have a 37% greater chance of developing depression than those who never or almost never consume them. As the amount ingested increases, so do the probabilities.

The researchers studied a group of nearly 9,000 people over a time of between 2 and 6 years as part of a long-term analysis. At the beginning of the study none of them had been diagnosed with depression or taken antidepressants. By the end, about 500 had been diagnosed or taken this medication.

The participants were asked to report how often they ate food from a certain list, which included things like burgers, sausages, pizza or sugary industrial pastries.

The authors observed that the more fast food you eat, the greater the risk of depression, and that the correlation also occurs in reverse: the more depressed you are, the more likely you are to eat large amounts of junk food.

What causes what?

In both cases, researchers have been unable to unravel how eating junk food causes depression, and neither if that happens or if it actually happens the other way around. What does seem clear is that both go hand in hand.

There are more factors involved: people who eat higher amounts of junk food are usually single or live alone, are less active, and have other bad eating habits, such as eating little fruit and vegetables as well as few healthy fatty acids in the form of nuts, fish or olive oil. They also tend to have bad habits outside the kitchen: smoking or working more than 45 hours a week.

While much remains to be investigated to clarify how fast food and depression relate to each other, it seems clear that reducing the amount of these foods we eat is not only good for our body, but also for our minds.