Excess body fat linked to increased risk of depression

New European research has found that the more extra fat a person carries, the higher their risk of depression.

Carried out by researchers from Aarhus University and Aarhus University Hospital, Denmark, the new study looked at data on 332,000 people taking part in UK Biobank, a long-term study which includes data on the association between genetic variants and fat mass, as well as data on 135,000 people with depression and 345,000 control subjects taking part in the Psychiatric Genomics Consortium, which contains information on the links between genetic variants and depression.

The researchers used a technique called Mendelian randomisation to look at the associations between fat mass, non-fat mass, height, and depression, but did not include body mass index (BMI) as it does not take into account build and muscle mass.

Mendelian randomisation involves studying genetic variants to see whether certain factors are associated with a higher or lower risk of disease. As it gives more reliable results, any associations found are more likely to suggest a direct relationship.

The findings, published in the journal Translational Psychiatry, showed that carrying ten kilograms of excess body fat (22lbs) could increase the risk of depression by 17 percent. In addition, the more excess fat, the greater the probability of developing depression.

When looking at height, short stature also appeared to be a causal risk factor for depression.

“Our study also indicated that the location of the fat on the body makes no difference to the risk of depression. This suggests that it is the psychological consequences of being overweight or obese which lead to the increased risk of depression, and not the direct biological effect of the fat,” said the study’s last author Dr. Søren Dinesen Østergaard.

“If the opposite was true we would have seen that fat located centrally on the body increased the risk the most, as it has the most damaging effect in biological terms.”

Østergaard also noted that the team’s findings are particularly important given the fact that almost 40 percent of the world’s adult population is overweight.

“In addition to the known physical consequences of obesity such as diabetes and cardiovascular disease, there is also a significant and now well-documented psychological component, which needs to be dealt with as well. This is yet another argument for resolving the obesity epidemic,” he said.

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