- A new observational study suggests that the more you gain extra-weight, the higher the chances of developing depression.
- The body part(s) where the fat is accumulated makes no difference to the probability of developing depression.
According to the National Center for Health Statistics report, more than 99 million adults in the United States are overweight and 70 million are obese. In fact, obesity rates in the U.S. are the highest in the world.
Obesity is defined as an excessive or abnormal accumulation of body fat. It is one of the major public health concerns, which increases the risk of series diseases such as type II diabetes, certain cancers, and cardiovascular disease.
Many observational studies have shown a connection between obesity and depression. A study conducted in 2010, for example, showed that depressed people were 58% more likely to become obese, while obese individuals were 55% more likely to develop depression.
However, these studies were based on Mendelian randomization – a technique from genetic epidemiology that uses data from genome-wide association studies to analyze the relationship between obesity and depression.
This technique measured obesity using BMI (short for body mass index) which is calculated solely on the basis of height and weight. Therefore, it doesn’t provide accurate data.
For example, many people (mostly athletes) with a low body fat mass and a large muscle mass have a BMI over 25. As per the common definition, this is considered as overweight. Obviously, this does not make much sense.
In order to get more accurate data, a research team from Aarhus University Hospital and Aarhus University conducted a new study, in which they examined data from two massive datasets.
1) The UK Biobank: consists of data on the association between physical measurements and genetic variants (from 332,000 people).
2) The Psychiatric Genomics Consortium: consists of data on the association between depression and genetic variants (from 480,000 people).
Reference: Translational Psychiatry | DOI:10.1038/s41398-019-0516-4
Researchers were able to dig deeper and analyze certain relationships between the amount of body fat and the risk of depression.
The objective of the research was to increase the understanding of the association between obesity and depression by evaluating the relations between certain biologically informative elements of BMI and depression via a Mendelian randomization study, using results from large genome-wide association studies.
Their primary analysis emphasizes on height, weight, whole-body fat mass, whole-body nonfat mass, and whole-body fat percentage, while secondary analysis focuses on the 15 specific regions of nonfat mass, fat mass, and fat percentage.
The study concludes that the more you gain extra-weight, the higher the chances of developing depression. To be more specific, adding 10 kg of extra fat raises the probability of depression by 17%.
The body part(s) where the fat is accumulated makes no difference to the chances of getting into depression. This means gaining excess weight is a result of psychological effects (instead of biological consequences) which ultimately leads to a higher risk of depression.
The findings clearly indicate that the risk of depression can be decreased by reducing the excess body fat. The best way to do that is, avoid unhealthy diet and focus on low-calorie, nutrient-dense foods.