There is a growing need to prevent obesity as a new study has found that higher body mass index (BMI) may impact your mental as well as physical health.

The study explored the aspects of physical health -- such as body weight, heart health and blood pressure -- to see whether a wide range of individuals with poorer physical health went on to be less happy and less satisfied with their lives or not. "Frequently, individuals are encouraged to lose weight because this will lead to better physical health, but for many this is not motivating enough," said senior author Claire Haworth from the University of Bristol, UK.

"Becoming happier and more satisfied with their lives might be the extra motivation needed to encourage more people to maintain a healthy weight," she added. For the study, published in the BMJ, with a technique called Mendelian randomisation, the research team examined whether poorer physical health causes lower mental well-being, or whether individuals with lower mental well-being are more likely to have problems with their physical health later on. 

This technique provides evidence of the direction of causation by using genetic variants that have been associated with physical health and mental well-being. The research team was able to test 11 measures of physical health including coronary artery disease, heart attack, cholesterol, blood pressure, body fat and body mass index (BMI).

The findings suggested a consistent causal effect of higher BMI on lower mental well-being. There was little evidence that the other physical health traits were leading to less happiness and life satisfaction, the team said. The same pattern of results was seen in a follow-up analysis using the UK Biobank cohort of over 300,000 individuals aged 40 to 70 years. "Results so far highlight the pressing need to tackle the obesity crisis because higher BMI is causing the population to be less happy and less satisfied with their lives," Haworth noted.