Unhappy meals – why fast food is bad for mental health

Studies have found a link between high-fat, high-sugar processed foods and the incidence of depression

A Burger King branch in the UAE. The company is offering the lower-methane burgers for a limited period in some stores in US cities such as Miami, New York, Austin, Portland and Los Angeles. Ryan CartShow more

Last week, the fast food company Burger King launched a new range of meals with the campaign slogan "No one is happy all the time". The chain's latest promotion boasts mood-matched food, including the blue meal, for sad people, and the salty meal, for those who are upset or bitter.

Coinciding with the start of Mental Health Awareness month in the US, an associated commercial features young people delivering a melancholic rap song, discussing emotions such as shame, despair and hopelessness. It ends with the catchy hashtag #FeelYourWay and a declaration of support for the American Mental Health Foundation.

It is all very slick, but I can’t help but feel that a fast food chain getting behind Mental Health Awareness month is counter-intuitive and counter-productive. Most of us have an implicit understanding that an unhealthy diet is not good for our psychological wellbeing, and it turns out that solid scientific research supports that idea.

The link between junk food and mental health issues has become increasingly apparent in recent years. For example, an article published last year in the journal Molecular Psychiatry reviewed 41 previous studies on the topic. It concluded that there was a clear association between a junk food diet and mental health issues. The study's authors suggest that "systemic inflammation" caused by processed foods with a high fat or sugar content "can directly increase the risk for depression".

At least five of the studies included in the review were large, longitudinal projects, following a total 32,908 adults from France, Australia, Spain, the US and the UK over several years. They indicated that a junk food diet tended to precede the onset of depression. In other words, depression is more likely to be a consequence of junk food consumption than the other way around.

Other diet-related research has identified a direct two-way link between the stomach and the brain. Referred to by scientists as the gut-brain connection, it also appears to have implications for our mental health. In fact, emerging research strongly suggests that some mental health problems may originate in the gut. This has led to further studies exploring the effectiveness of diet-based interventions, such as the use of psychobiotics – dietary supplements that improve mental health by changing the mixture of bacteria in the gut. Fast food has the opposite effect.

Research on the use of psychobiotic supplements is at an early stage, but the initial findings are promising. For example, a study published last year in the journal Bipolar Disorder found that bipolar patients discharged from hospital with a probiotic supplement had far lower rates of relapse over the next six months, compared to patients discharged with a placebo.

Mental health issues are a topic of global strategic importance. In many nations, increasing numbers of people, especially the young, are experiencing depression and anxiety. The 2019 Arab Youth Survey reported that almost one-third of the 3,300 respondents, from 15 Arabic-speaking territories, personally know somebody who is experiencing a mental health issue.  In this context, raising awareness of mental health issues while marketing junk food seems less than helpful.

The Burger King campaign also appears to encourage emotional eating. Comfort eating might be OK now and again, but if indulged in too frequently it can spiral out of control, leading to conditions such as binge eating disorders and bulimia nervosa. These conditions are associated with physical stress on the body as well as psychological stress on the mind. Eating as a reaction to emotional distress might feel good in the moment, but it has the potential to make matters worse in the long-term.

Many of us are fortunate enough to be able to pick and choose what we eat. If we want to make junk food a regular part of our diet, then that is up to us. The evidence of a link between mental health issues and such a diet, however, might make us start to question some of our choices. At a time when food is on many of our minds, it is worth thinking about the quality of what we put into our bodies and the unseen effects it may have.

Justin Thomas is a professor of psychology at Zayed University