Do Mental Health Problems Predict Obesity?

Members of the Canadian Obesity Network will have noticed that the last edition of CONDUIT magazine focussed on mental health (CONDUIT Magazine online).

As often blogged about in the past, I firmly believe that it will be impossible to deal with the obesity epidemic unless we fully acknowledge the importance of mental issues both as drivers and as important barriers to treatment. As long as we continue our “symptomatic” approach to obesity management which focusses on calories in and calories out rather than on addressing the causal factors that underly caloric overconsumption and/or underutilisation, we will be stuck in an endless cycle of weight-loss and regain.

The importance of mental health issues in overweight and obese patients was once again demonstrated in a paper by Mika Kivimäki and colleagues from the Department of Epidemiology and Public Health, University College London, UK, published in last week’s issue of the British Medical Journal.

The study looks at the 4363 adults (28% female, mean age 44 years at baseline) in the Whitehall II Study, a prospective cohort study in London civil servants with four measures of common mental disorders (e.g. depression, anxiety, etc.) and obesity over 19 years.

In models adjusted for age, sex, and BMI at baseline, odds ratios for obesity at the fourth screening were 1.33, 1.64, and 2.01 for participants with common mental disorder at one, two, or three preceding screenings compared with people free from common mental disorders.

Although obesity appeared to also predicted future risk of common mental disorder, this association was lost when people with mental disorders at baseline were excluded. Thus, the study does not support the notion that excess weight is the primary driver of poor mental health. 

Rather is appears from this study that the presence of common mental disorders increases the future risk of obesity particularly in people with chronic or repeat episodes of common mental disorders.

There are at least four plausible reasons why people with mental health problems may be at increased risk for weight gain:

1) Common mental disorders are associated with changes in ingestive behaviour, which could influence future changes in adiposity.

2) Physical inactivity is more prevalent among people with mental health problems.

3) Commonly used drug treatments for mentaldisorders have known side effects that may result in weight gain.

4) Biological factors, such as dysregulation of the hypothalamic-pituitary-adrenocortical axis, may promote overeating and promote fat storage. 

While we should now by no means assume that all overweight and obese individuals have mental health issues, in those that do, addressing their mental health problems may be the key to weight stablisation and control. 

Edmonton, Alberta