A new study has shown that being overweight causes depression and lowers well-being. It further indicated that both social and physical factors may play a task in the effect. The findings of the study were published in the journal 'Human Molecular Genetics'. With one in four adults considered to be obese in the UK and growing numbers of children affected, obesity is a global health challenge. While the risks of being obese on physical health are well known, researchers are now discovering that being overweight can also have a significant impact on mental health.
The study sought to investigate why a body of proof now shows that higher BMI causes depression. The team used genetic analysis, known as Mendelian Randomisation, to examine whether the causal link is the result of psychosocial pathways, such as societal influences and social stigma, or physical pathways, such as metabolic conditions linked to higher BMI. Such diseases include high blood pressure, type 2 diabetes and cardiovascular disease. In research led by the University of Exeter and funded by the Academy of Medical Sciences, the team examined genetic data from more than 145,000 participants from the UK Biobank with detailed mental health data available.
In a multifaceted study, the researchers examined genetic variants linked to higher BMI, as well as outcomes from a clinically relevant mental health questionnaire designed to assess levels of depression, anxiety and wellbeing. To examine which pathways may be active in causing depression in people with higher BMI, the team also interrogated two sets of previously discovered genetic variants. One set of genes makes people fatter, yet metabolically healthier, meaning they were less likely to develop conditions linked to higher BMI, such as high blood pressure and type 2 diabetes. The second set of genes analysed make people fatter and metabolically unhealthy, or more prone to such conditions.