Is obesity really driving depression?

Obesity might just be one of the leading causes of depression according to a new study that found a link between poor mental health and the rise in global rates of excess fat.  

Global obesity has more than tripled since 1975 based on figures from the World Health Organization, which noted 1.9 billion people were considered overweight back in 2016. 

Rates of obesity haven’t improved over the last decade and while most people focus on the poor health outcomes overweight individuals can suffer, there are other big dangers. 

Mental health disorders as a result of weight have emerged as one negative outcome of a person's weight and their rise has coincided with obesity rates according to Psy Post. 

Previous research into the link between mental health and a person's weight has shown those who struggle with obesity are 55% more likely to be depressed over their lifetime. 

However, a recent meta-analytic review of previous research has revealed that obesity isn’t just correlated to depression, it might be one of the leading causes of depression. 

Researchers from the University of Finland used Mendelian randomization to examine a wide variety of previous studies to draw conclusions about obesity’s role in depression. 

Mendelian randomization is a process by which researchers look at genetic information to see if a behavior or trait of an individual is caused by a specific outcome, Pst Post noted. 

“This helps them determine if there is a real cause-and-effect relationship between the exposure and the outcome,” the psychology and neuroscience news website continued. 

Researchers in our case were trying to determine if obesity—the behavior or trait—was linked to depression—the specific outcome—based on eight Mendelian randomization studies they analyzed. 

The results from the eight studies examined showed those suffering from obesity had a much higher risk of depression compared to people who were not considered obese. 

The researchers examined the changes in psychological distress as well as the rates of obesity reported by the surveys and examined the decades between 1991 and 2016. 

What the researchers discovered was that obesity did play a role in the development of depression, albeit a modest one. The study’s authors predicted a 0.6 percentage-point increase in psychological distress across the populations they looked at from 1991 to 2016.

“In sum, obesity seems to be a causal risk factor for depression, increasing its odds by 33%. Between 15% and 20% of the general population are estimated to suffer from at least moderate psychological distress,” the study’s authors wrote.  

“The doubling of obesity prevalence from the 1990s–2010s would have increased this prevalence by one-half percentage points,” the study's authors added. 

While it may not seem like much, this discovery can help us change health outcomes for those suffering from depression. Knowing weight could be causing a rise in depression can help direct public health policy in a direction that will solve the growing problem.