Obesity linked to anxiety, and depression

Mental health disorders such as anxiety and depression are associated with obesity according to a new study from the University of Otago, Wellington, New Zealand. The research found there are associations between obesity and some anxiety disorders, and less strong links with obesity and depression. This is the first study to have examined links between all anxiety disorders and obesity.

The findings indicate that in the general population people with obesity are more likely to have certain mental disorders than people without obesity. However, lead investigator and clinical psychologist Dr Kate Scott says the findings do not prove mental health disorders cause obesity, or vice versa.

"Mental disorders are unlikely to play a big part in the recent increase in obesity, but they may make it harder for some individuals to resist the pressures of the obesogenic environment in which we now live," says Dr Scott.

"We have shown there are clear links between obesity and post-traumatic stress disorder or PTSD, and social phobia, and also to a lesser degree with depression. The strongest association is between obesity and PTSD, and this is a new finding."

The other main thrust of the research was to investigate questions about whether the association between obesity and mental disorders is more characteristic of some groups in society than others. The study came up with some clear findings:

• Obesity and mood disorders like depression are only associated among women, and people with no educational qualifications.
• By contrast, the association between obesity and anxiety disorders occurs in both men and women, and is not affected by education.

There is evidence that some kind of emotionally determined overeating is associated with obesity. Anxiety is one of the negative emotions postulated as a trigger for emotional eating and there is evidence for anxiety increasing food consumption among obese compared to non-obese persons.

In the wider population anxiety may be more associated with obesity than depression, because anxiety is not so commonly associated with appetite loss.

Regarding post-traumatic stress disorder, other studies have shown links between childhood trauma such as sex abuse and adult obesity, as well as between past trauma and current binge-eating. The researchers say that it is more likely PTSD would lead to obesity than the reverse, and this is backed up by other studies.

Dr Scott says more research needs to be done into the role that mental disorders, in particular anxiety, might play in the development or maintenance of obesity. This would assist clinicians working in the area.

This research was funded by the Ministry of Health, the Health Research Council, the Alcohol Advisory Council of New Zealand and the New Zealand Lottery Grants Board.

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Scott KM, McGee MA, J. Wells JE, Oakley Browne MA. Obesity and mental disorders in the adult general population. J Psychosom Res. 2008 Jan;64(1):97-105   [Full text]