Carrying ten kilograms (22 pounds) of excess body fat can increase a person’s risk of depression by 17 percent, according to a new study from Aarhus University and Aarhus University Hospital in Denmark.
In fact, the research shows that the more excess fat a person has, the greater the probability of developing depression — and the researchers believe it is the psychological aspect of carrying the extra weight, not the biological effects of the fat, that is driving the depression.
“Our study also indicated that the location of the fat on the body makes no difference to the risk of depression,” says Dr. Søren Dinesen Østergaard, a professor at the Department of Clinical Medicine at Aarhus University. “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.”
“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.”
The findings are published in the journal Translational Psychiatry.
Previous studies on this topic have predominantly used body mass index (BMI) to measure obesity. BMI is calculated solely on the basis of body weight and height and is therefore a fairly crude measure, which does not, for example, take build and muscle mass into account.
“BMI is an inaccurate way of measuring overweight and obesity. Many elite athletes with a large muscle mass and a low body fat mass will have a BMI above 25, which is classified as overweight according to the common definition. This obviously doesn’t make much sense,” said Østergaard.
“Therefore, one of the strengths of our study is that we’ve been able to zoom in and look at the specific relationship between the amount of body fat and the risk of depression.”
In the study, the researchers analyzed data from two large genetic data sets: the UK Biobank, which contains information on the association between genetic variants and fat mass based on a study of 330,000 people, including body fat mass distributed around parts of the body; and the Psychiatric Genomics Consortium, which contains data on the association between genetic variants and depression based on a study of 135,000 people with depression and 345,000 control subjects.
Østergaard emphasized that the findings are particularly significant in light of 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, before emphasizing that it is important to have a balanced approach to the issue.
“As it appears to be the psychological consequences of obesity, such as a negative body image and low self-esteem that is the main driving force behind the increased risk of depression, society’s efforts to combat obesity must not stigmatise, as this will probably increase the risk of depression even further. It is important to bear this in mind so we can avoid doing more harm than good in the effort to curb the obesity epidemic,” Østergaard said.
The Aarhus University research group included Maria S. Speed, Oskar H. Jefsen, Anders D. Børglum, Doug Speed and Østergaard.
Source: Aarhus University