People who were obese had more severe depression and lower mental well-being. Relationships between weight and depression were more significant in people who were female, younger and have diabetes, according to a recent report of middle-aged and older adults published March 6 in PLOS ONE.
Data came from the Cork and Kerry Diabetes and Heart Disease phase II clinical study that ran from 2010 to 2011. The data was collected at a primary care center in Ireland and included 1,821 participants between the ages of 46 and 73, according to the study. (The country has some of the highest rates of mental illness in Europe, the authors pointed out.)
Researchers recorded participants’ body mass index (BMI) and waist-height ratio (WHR), and collected responses from questionnaires. Possible confounding factors recorded included smoking and alcohol consumption, sex, age, education, physical activity and chronic diseases including diabetes, cancer and cardiovascular disease.
BMI is a measure of total body fat, whereas WHR reflects where fat is deposited. The results showed both measures of body fat were significantly associated with depression.
People with higher body fat — regardless of sex, lifestyle and other diseases — were more likely to experience depression, the results showed. The link was more pronounced in females, but occurred in both sexes. Findings aligned with previous evidence showing an increased risk for new-onset depression in people who are obese.
Obesity and depression both interfere with the chemical balance of neural transmission circuits, which disrupt the endocrine axis and cause inflammation, increased oxidative stress, mitochondrial dysfunction that compromises the energy metabolism of the body, and neurodegeneration.
The authors said they’re still not sure whether obesity causes depression or vice versa, and more research is needed.
“These findings suggest that increased adiposity [fat] is significantly associated with poorer mental health, independent of lifestyle factors and disease conditions,” the authors wrote, calling for targeted strategies to lower depression including weight-management measures.
