Obesity related to depression risk among older adults

By Dr. Liji Thomas, MDReviewed by Benedette Cuffari, M.Sc.Mar 12 2024

A new study in PLOS ONE discusses the association between depression and obesity.

Study: Associations between adiposity measures and depression and well-being scores: A cross-sectional analysis of middle- to older-aged adults. Image Credit: Creative Images / Shutterstock.com

Obesity and depression

Previous research suggests a close relationship between obesity and depression, with obesity reported in almost 60% of people in one group with severe depression. This study also indicated that obesity was 1.2-1.5 times more likely in people with major depression; however, conflicting results on this association have been reported in other studies.

A healthy lifestyle is associated with mental health benefits, whereas an unhealthy lifestyle have been shown to increase the risk of depression. This is important, as lifestyle factors can be modified to reduce the risk of poor mental health.

The current study sought to produce consistent and reproducible data using two different measures of fat mass or adiposity to assess the association with mental health. More specifically, both body mass index (BMI) and waist-height ratio (WHR) were examined for their possible association with depression and mental health after considering possible confounding factors.

About the study

The current study obtained data from the Cork and Kerry Diabetes and Heart Disease phase II clinical study that was conducted between May 1, 2010, and April 30, 2011. Random sampling was performed from a primary care center, with the final cohort including 1,800 participants.

BMI and WHR measurements were obtained after testing study participants for diabetes in the fasting state. Health and lifestyle characteristics were also assessed by a questionnaire, along with a food frequency questionnaire to evaluate dietary factors that were presented as a Dietary Approaches to Stop Hypertension (DASH) diet score.

Smoking, alcohol consumption, demographic factors including sex, age and education, physical activity, and chronic diseases, specifically diabetes, cardiovascular disease, and cancers, were considered as potential confounding factors.

What did the study show?

More severe depression and lower mental wellbeing was associated with being female, younger, and diabetic, but negatively associated with physical activity. Study participants with lower education and those who did not drink heavily had higher wellbeing scores.

BMI reflects total body fat, whereas WHR reflects central fat deposition or visceral fat. In the current study, both measures of body fat were significantly associated with depression.

Individuals with higher body fat were more likely to be depressed in both sexes, even after lifestyle and specified diseases associated with obesity were considered. This association was stronger in females as compared to males; however, both were significant.

Increased adiposity is related to mental health.”

How does obesity affect mental health?

The study findings corroborate previous research suggesting an increased risk of new-onset depression among obese individuals. This association could be mediated by reduced self-esteem, self-image, with satisfaction with oneself due to obesity, all of which can increase the risk of depression.

Social factors may also affect this association, as obese individuals are often mocked or discriminated against in social situations. Obesity may also contribute to chronic pain in the joints or trigger fibromyalgia, which may worsen symptoms of depression.

Both obesity and depression interfere with the chemical balance of neural transmission circuits, thereby disrupting the endocrine axis to cause inflammation, increased oxidative stress, mitochondrial dysfunction that compromises the energy metabolism of the body, and, ultimately, neurodegeneration.

Disruption of the neural and endocrine signaling systems that regulate energy production and consumption by the body may also be contribute to the association between obesity and depression, as hormones like insulin and leptin are also involved in food consumption. Moreover, obesity and depression may be related to neural pathways that connect these homeostatic responses with circuits that help regulate mood.

Childhood poverty and other indicators of underprivileged status predict adult depression. This could be mediated by adverse environmental and lifestyle factors, family instability, and increased life stress.

What are the implications?

It remains unclear whether obesity causes depression or vice versa from the findings of this cross-sectional study. Thus, further research is needed to elucidate the mechanisms responsible for this association.

Targeted interventions for reducing depression should include better weight management population-level measures, particularly in middle- to older-aged populations.”