Even with higher levels of education, women who are obese have double the risk of depression when compared to women of normal weight, new research shows.
Researchers used standard weight categories: normal weight (BMI 18.5-24.9), overweight (BMI 25-29.9), obese I (30-34.9), obese II (35-39.9), and obese III (BMI greater than 39.9). The findings showed similar results for obese II and III participants; however, not enough participants were available for statistical validation.
The BMI classifications are related to body-fat levels and predict the likelihood of developing obesity-related health problems.
“Previous research has shown an association of depression and obesity with low education, but we’re showing it also exists with women who have higher education as well,” says lead author Ashley Kranjac, postdoctoral fellow in population health at Rice University.
“I was surprised by the finding. Usually higher education is associated with all the good things, like higher income, better neighbourhoods, greater access to health care, and better overall health, and you’d never think education and obesity combined could have this effect on mental health.”
Published in the journal Obesity Research and Clinical Practice, the study included a random sample of 1928 healthy women aged 35-80. Researchers used New York State Department of Motor Vehicle records and information from the Health Care Finance Association to identify potential participants.
Trained professional interviewers took physical measurements for body-mass index and conducted standardised, in-person interviews. The detailed interviews included questions dealing with demographic traits, medical history, diet, and several aspects of alcohol consumption throughout the person’s lifetime. All participants also completed the Centre for Epidemiologic Studies Depression Scale questionnaire, a tool designed to measure depression status among the general population.
Recent research indicates that women have significantly more chronic difficulties and face more cumulative disadvantages compared with men, Kranjac says.
“Our study provides evidence that in the examination of ongoing strain and cumulative stressors leading to depressive symptoms in women’s lives, considering weight status and other factors concurrently may be informative.
“What this means in terms of treatment programs for clinicians is that they need to consider education and obesity and depressive symptoms in combination when considering treatment options. You can’t think of these things in isolation, because they don’t work independently of each other.”
The study also confirms previous research that found BMI was significantly different for those who reported being depressed compared with those who were not depressed:
Depressed women were more likely to be obese.
Depressed women were more often older, not married, less educated, a former or current smoker, less physically active, consumed more calories, averaged less than eight hours of sleep, and had a lower income.
Obese I women’s odds of depressive symptoms were 43 per cent higher than normal weight women, and the odds for obese II/ III women were approximately 57 per cent higher than for women of normal weight.
All of the women who participated in the study provided written informed consent. The research team pointed out that the study does have some limitations, including not knowing if a participant’s depression resulted from weight gain or vice versa, weight fluctuation, geographical influencers (local economy), and the small number of racial and ethnic minority group members sampled in the study.
However, the findings are significant and are applicable to a subset of the larger society who have a BMI of obesity I in the United States, Kranjac says.
“To our knowledge, no study has used a large, population-based sample of women to study the association between depression, weight status and education level. By studying this association in healthy women without other chronic diseases or disorders, we are better able to understand the associations between depression, increased weight status and the impact of educational attainment.”
The National Institutes of Health, the National Institute on Alcohol Abuse and Alcoholism, the Department of Defence, and the National Cancer Institute funded the work.
This article first appeared on ‘The Australian’ on 24 March 2016.