Being overweight 'significantly associated' with poorer mental health 

The researchers found 'significant relationships' between higher BMI (body mass index) and having a greater number of depressive symptoms, independent of lifestyle and disease. 

Being overweight is “significantly associated” with poorer mental health and this link is stronger among women than men, Irish research has found.

University College Cork researchers analysed data on 1,821 adults in the Mitchelstown region to examine links between BMI and mental health.

The researchers found “significant relationships” between higher BMI (body mass index) and having a greater number of depressive symptoms, independent of lifestyle and disease. 

An increase in weight can exacerbate depression, they found, through prejudice, discrimination or by the person stigmatising themselves.

"The chronic pain that is directly caused by obesity, such as joint pain, back pain and fibromyalgia, is also known to result in depressive symptoms," the study stated.  

However, they also stated it is possible increased body fat (adiposity) “may be a consequence of poorer mental health and not a cause”.

The team advised: “Targeted interventions for reducing depression should include better population-level weight management measures.” 

This study was carried out by Dr Caoimhe Lonergan, Dr Seán Millar, and Dr Zubair Kabir from the UCC School of Public Health.

Dr Millar said the research suggests links between adiposity and depressive symptoms are “independent of potential confounders such smoking, alcohol use, low-level physical activity and chronic conditions”.

He added, however: “Future studies using prospective data, in diverse populations, are needed to confirm these findings. In addition, further research is required to identify the mechanisms which links overweight and obesity with depression.” 

They relied on data previously collected during Phase 2 of the Cork and Kerry Diabetes and Heart Disease Study, from adults aged 46 to 73.

The team found: “BMI and waist-height ratio had a significant positive association with depression scores and a significant inverse association with well-being scores in males and females.” 

In addition, they found: “relationships between measures of adiposity and depression were found to be stronger in females than males.” 

As well as BMI, researchers also noted participants’ waist-height ratio.

They explained that: "BMI is a measure of general adiposity while waist-height ratio is a measure of central adiposity.”

They said while BMI is more often used in clinical settings, it has been "criticised as being an inaccurate measure of body fat.” 

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BMI was calculated as weight in kilograms divided by the square of height in meters.

The height/weight ratio was measured by dividing height into waist circumference measurements.

The study "Obesity indices and mental health" is published in the journal PLOS One this week.