The study, conducted by researchers from Group Health Center for Health Studies, found that an obese person is about 25% more likely than a non-obese person to have a mood or anxiety disorder, such as depression. It also indicated that, among caucasian Americans and more educated people who are obese, that likelihood may be as high as 44%.
While the study did not show whether obesity leads to depression or vice versa, “it’s almost certain that the association works in both directions,” according to Dr Greg Simon, a Group Health psychiatrist and the lead author of the study.
The researchers also found a negative association between obesity and substance abuse. That is, an obese person is 25% less likely than a non-obese person to have had a substance abuse disorder sometime in their lives.
“Understanding the connection between obesity and depression is an important public health issue because both of these conditions are so common and have a significant impact on our health care systems,” Dr Simon explained. He pointed to the evidence that an average American has a 30% chance of being obese. This study shows that, when a person is depressed, the odds of also becoming obese are as high as 40%.
The study was conducted among a nationally representative sample of 9,125 adult men and women. While previous studies have shown a connection between obesity and depression, this is the largest and most representative study of the two problems in the US population.
In addition, unlike many previous studies that show a link between obesity and depression among women only, this study revealed a strong link in both genders.